1309 lines
524 KiB
HTML
1309 lines
524 KiB
HTML
<!DOCTYPE html><html lang="en"><head><link rel="stylesheet" href="./mini.css"><title>30 seconds of code</title><meta charset="utf-8"><meta name="description" content="Curated collection of useful Javascript snippets that you can understand in 30 seconds or less."><meta name="keywords" content="javascript, snippets, code, programming"><meta name="author" content="Angelos Chalaris (chalarangelo@gmail.com)"><meta name="viewport" content="width=device-width,initial-scale=1"><meta property="og:title" content="30 seconds of code"><meta property="og:description" content="Curated collection of useful Javascript snippets that you can understand in 30 seconds or less."/><meta property="og:type" content="website"/><meta property="og:image" content="favicon.png"><link rel="icon" type="image/png" href="favicon.png"><script>const search = (node) => {
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5.875rem);overflow:hidden"><input id="doc-drawer-checkbox" class="drawer" value="on" type="checkbox"><nav class="col-md-4 col-lg-3" style="border-top:0"><div class="group"><input class="search" type="text" id="searchInput" onkeyup="search(this)"><label id="search-label">Search for snippet...</label></div><label for="doc-drawer-checkbox" class="button drawer-close"></label><h3>Adapter</h3><a class="sublink-1" tags="adapter,function" href="#call">call</a> <a class="sublink-1" tags="adapter,function,array" href="#collectinto">collectInto</a> <a class="sublink-1" tags="adapter,function" href="#flip">flip</a> <a class="sublink-1" tags="adapter,function" href="#pipefunctions">pipeFunctions</a> <a class="sublink-1" tags="adapter,function,promise" href="#promisify">promisify</a> <a class="sublink-1" tags="adapter" href="#spreadover">spreadOver</a><h3>Array</h3><a class="sublink-1" tags="array" href="#chunk">chunk</a> <a class="sublink-1" tags="array" href="#compact">compact</a> <a class="sublink-1" tags="array,object" href="#countby">countBy</a> <a class="sublink-1" tags="array" href="#countoccurrences">countOccurrences</a> <a class="sublink-1" tags="array,recursion" href="#deepflatten">deepFlatten</a> <a class="sublink-1" tags="array,math" href="#difference">difference</a> <a class="sublink-1" tags="array,function" href="#differencewith">differenceWith</a> <a class="sublink-1" tags="array" href="#distinctvaluesofarray">distinctValuesOfArray</a> <a class="sublink-1" tags="array,function" href="#dropelements">dropElements</a> <a class="sublink-1" tags="array" href="#dropright">dropRight</a> <a class="sublink-1" tags="array" href="#everynth">everyNth</a> <a class="sublink-1" tags="array" href="#filternonunique">filterNonUnique</a> <a class="sublink-1" tags="array" href="#findlast">findLast</a> <a class="sublink-1" tags="array" href="#flatten">flatten</a> <a class="sublink-1" tags="array,function" href="#foreachright">forEachRight</a> <a class="sublink-1" tags="array,object" href="#groupby">groupBy</a> <a class="sublink-1" tags="array" href="#head">head</a> <a class="sublink-1" tags="array" href="#indexofall">indexOfAll</a> <a class="sublink-1" tags="array" href="#initial">initial</a> <a class="sublink-1" tags="array" href="#initialize2darray">initialize2DArray</a> <a class="sublink-1" tags="array,math" href="#initializearraywithrange">initializeArrayWithRange</a> <a class="sublink-1" tags="array,amth" href="#initializearraywithvalues">initializeArrayWithValues</a> <a class="sublink-1" tags="array,math" href="#intersection">intersection</a> <a class="sublink-1" tags="array" href="#issorted">isSorted</a> <a class="sublink-1" tags="array" href="#join">join</a> <a class="sublink-1" tags="array" href="#last">last</a> <a class="sublink-1" tags="array,string,utility" href="#longestitem">longestItem</a> <a class="sublink-1" tags="array,object" href="#mapobject">mapObject</a> <a class="sublink-1" tags="array,math" href="#maxn">maxN</a> <a class="sublink-1" tags="array,amth" href="#minn">minN</a> <a class="sublink-1" tags="array" href="#nthelement">nthElement</a> <a class="sublink-1" tags="array,object,function" href="#partition">partition</a> <a class="sublink-1" tags="array" href="#pick">pick</a> <a class="sublink-1" tags="array" href="#pull">pull</a> <a class="sublink-1" tags="array" href="#pullatindex">pullAtIndex</a> <a class="sublink-1" tags="array" href="#pullatvalue">pullAtValue</a> <a class="sublink-1" tags="array" href="#reducedfilter">reducedFilter</a> <a class="sublink-1" tags="array" href="#remove">remove</a> <a class="sublink-1" tags="array,random" href="#sample">sample</a> <a class="sublink-1" tags="array,random" href="#samplesize">sampleSize</a> <a class="sublink-1" tags="array,random" href="#shuffle">shuffle</a> <a class="sublink-1" tags="array,math" href="#similarity">similarity</a> <a class="sublink-1" tags="array,math" href="#sortedindex">sortedIndex</a> <a class="sublink-1" tags="array,math" href="#symmetricdifference">symmetricDifference</a> <a class="sublink-1" tags="array" href="#tail">tail</a> <a class="sublink-1" tags="array" href="#take">take</a> <a class="sublink-1" tags="array" href="#takeright">takeRight</a> <a class="sublink-1" tags="array,math" href="#union">union</a> <a class="sublink-1" tags="array" href="#without">without</a> <a class="sublink-1" tags="array" href="#zip">zip</a> <a class="sublink-1" tags="array,object" href="#zipobject">zipObject</a><h3>Browser</h3><a class="sublink-1" tags="browser,array" href="#arraytohtmllist">arrayToHtmlList</a> <a class="sublink-1" tags="browser" href="#bottomvisible">bottomVisible</a> <a class="sublink-1" tags="browser,string,advanced" href="#copytoclipboard">copyToClipboard</a> <a class="sublink-1" tags="browser,utility" href="#createelement">createElement</a> <a class="sublink-1" tags="browser,event,advanced" href="#createeventhub">createEventHub</a> <a class="sublink-1" tags="browser,url" href="#currenturl">currentURL</a> <a class="sublink-1" tags="browser" href="#detectdevicetype">detectDeviceType</a> <a class="sublink-1" tags="browser" href="#elementisvisibleinviewport">elementIsVisibleInViewport</a> <a class="sublink-1" tags="browser" href="#getscrollposition">getScrollPosition</a> <a class="sublink-1" tags="browser,css" href="#getstyle">getStyle</a> <a class="sublink-1" tags="browser,css" href="#hasclass">hasClass</a> <a class="sublink-1" tags="browser,css" href="#hide">hide</a> <a class="sublink-1" tags="browser,url" href="#httpsredirect">httpsRedirect</a> <a class="sublink-1" tags="browser,event" href="#off">off</a> <a class="sublink-1" tags="browser,event" href="#on">on</a> <a class="sublink-1" tags="browser,event,advanced" href="#onuserinputchange">onUserInputChange</a> <a class="sublink-1" tags="browser,url" href="#redirect">redirect</a> <a class="sublink-1" tags="browser,function,advanced,promise,url" href="#runasync">runAsync</a> <a class="sublink-1" tags="browser" href="#scrolltotop">scrollToTop</a> <a class="sublink-1" tags="browser" href="#setstyle">setStyle</a> <a class="sublink-1" tags="browser,css" href="#show">show</a> <a class="sublink-1" tags="browser" href="#toggleclass">toggleClass</a> <a class="sublink-1" tags="browser,utility,random" href="#uuidgeneratorbrowser">UUIDGeneratorBrowser</a><h3>Date</h3><a class="sublink-1" tags="date,math,string,utility" href="#formatduration">formatDuration</a> <a class="sublink-1" tags="date" href="#getdaysdiffbetweendates">getDaysDiffBetweenDates</a> <a class="sublink-1" tags="date" href="#tomorrow">tomorrow</a><h3>Function</h3><a class="sublink-1" tags="function" href="#chainasync">chainAsync</a> <a class="sublink-1" tags="function" href="#compose">compose</a> <a class="sublink-1" tags="function,recursion" href="#curry">curry</a> <a class="sublink-1" tags="function" href="#defer">defer</a> <a class="sublink-1" tags="function,utility" href="#functionname">functionName</a> <a class="sublink-1" tags="function" href="#memoize">memoize</a> <a class="sublink-1" tags="function" href="#negate">negate</a> <a class="sublink-1" tags="function" href="#once">once</a> <a class="sublink-1" tags="function,promise" href="#runpromisesinseries">runPromisesInSeries</a> <a class="sublink-1" tags="function,promise" href="#sleep">sleep</a><h3>Math</h3><a class="sublink-1" tags="math,array" href="#average">average</a> <a class="sublink-1" tags="math,array,function" href="#averageby">averageBy</a> <a class="sublink-1" tags="math" href="#clampnumber">clampNumber</a> <a class="sublink-1" tags="math,array" href="#digitize">digitize</a> <a class="sublink-1" tags="math" href="#distance">distance</a> <a class="sublink-1" tags="math,array,advanced" href="#elo">elo</a> <a class="sublink-1" tags="math,recursion" href="#factorial">factorial</a> <a class="sublink-1" tags="math,array" href="#fibonacci">fibonacci</a> <a class="sublink-1" tags="math,recursion" href="#gcd">gcd</a> <a class="sublink-1" tags="math" href="#geometricprogression">geometricProgression</a> <a class="sublink-1" tags="math" href="#hammingdistance">hammingDistance</a> <a class="sublink-1" tags="math" href="#inrange">inRange</a> <a class="sublink-1" tags="math" href="#isdivisible">isDivisible</a> <a class="sublink-1" tags="math" href="#iseven">isEven</a> <a class="sublink-1" tags="math" href="#isprime">isPrime</a> <a class="sublink-1" tags="math,recursion" href="#lcm">lcm</a> <a class="sublink-1" tags="math,utility" href="#luhncheck">luhnCheck</a> <a class="sublink-1" tags="math,array,function" href="#maxby">maxBy</a> <a class="sublink-1" tags="math,array" href="#median">median</a> <a class="sublink-1" tags="math,array,function" href="#minby">minBy</a> <a class="sublink-1" tags="math" href="#percentile">percentile</a> <a class="sublink-1" tags="math" href="#powerset">powerset</a> <a class="sublink-1" tags="math,array" href="#primes">primes</a> <a class="sublink-1" tags="math,utility,random" href="#randomintegerinrange">randomIntegerInRange</a> <a class="sublink-1" tags="math,utility,random" href="#randomnumberinrange">randomNumberInRange</a> <a class="sublink-1" tags="math" href="#round">round</a> <a class="sublink-1" tags="math,utility" href="#sdbm">sdbm</a> <a class="sublink-1" tags="math,array" href="#standarddeviation">standardDeviation</a> <a class="sublink-1" tags="math,array" href="#sum">sum</a> <a class="sublink-1" tags="math,array,function" href="#sumby">sumBy</a> <a class="sublink-1" tags="math" href="#sumpower">sumPower</a> <a class="sublink-1" tags="math" href="#tosafeinteger">toSafeInteger</a><h3>Node</h3><a class="sublink-1" tags="node" href="#hasflags">hasFlags</a> <a class="sublink-1" tags="node" href="#istravisci">isTravisCI</a> <a class="sublink-1" tags="node,json" href="#jsontofile">JSONToFile</a> <a class="sublink-1" tags="node,array,string" href="#readfilelines">readFileLines</a> <a class="sublink-1" tags="node,string" href="#untildify">untildify</a> <a class="sublink-1" tags="node,utility,random" href="#uuidgeneratornode">UUIDGeneratorNode</a><h3>Object</h3><a class="sublink-1" tags="object,json" href="#cleanobj">cleanObj</a> <a class="sublink-1" tags="object,function" href="#functions">functions</a> <a class="sublink-1" tags="object" href="#invertkeyvalues">invertKeyValues</a> <a class="sublink-1" tags="object" href="#lowercasekeys">lowercaseKeys</a> <a class="sublink-1" tags="object,function" href="#mapkeys">mapKeys</a> <a class="sublink-1" tags="object,function" href="#mapvalues">mapValues</a> <a class="sublink-1" tags="object,array" href="#merge">merge</a> <a class="sublink-1" tags="object,array" href="#objectfrompairs">objectFromPairs</a> <a class="sublink-1" tags="object,array" href="#objecttopairs">objectToPairs</a> <a class="sublink-1" tags="object,array" href="#orderby">orderBy</a> <a class="sublink-1" tags="object" href="#select">select</a> <a class="sublink-1" tags="object" href="#shallowclone">shallowClone</a> <a class="sublink-1" tags="object,array,string" href="#size">size</a> <a class="sublink-1" tags="object,array" href="#transform">transform</a> <a class="sublink-1" tags="object,logic,array" href="#truthcheckcollection">truthCheckCollection</a><h3>String</h3><a class="sublink-1" tags="string,recursion" href="#anagrams">anagrams</a> <a class="sublink-1" tags="string" href="#bytesize">byteSize</a> <a class="sublink-1" tags="string,array" href="#capitalize">capitalize</a> <a class="sublink-1" tags="string,regexp" href="#capitalizeeveryword">capitalizeEveryWord</a> <a class="sublink-1" tags="string,array" href="#decapitalize">decapitalize</a> <a class="sublink-1" tags="string,browser,regexp" href="#escapehtml">escapeHTML</a> <a class="sublink-1" tags="string,regexp" href="#escaperegexp">escapeRegExp</a> <a class="sublink-1" tags="string" href="#fromcamelcase">fromCamelCase</a> <a class="sublink-1" tags="string,utility,browser,url" href="#isabsoluteurl">isAbsoluteURL</a> <a class="sublink-1" tags="string,utility" href="#islowercase">isLowerCase</a> <a class="sublink-1" tags="string,utility" href="#isuppercase">isUpperCase</a> <a class="sublink-1" tags="string,utility,regexp" href="#mask">mask</a> <a class="sublink-1" tags="string" href="#palindrome">palindrome</a> <a class="sublink-1" tags="string" href="#pluralize">pluralize</a> <a class="sublink-1" tags="string,array" href="#reversestring">reverseString</a> <a class="sublink-1" tags="string" href="#sortcharactersinstring">sortCharactersInString</a> <a class="sublink-1" tags="string" href="#splitlines">splitLines</a> <a class="sublink-1" tags="string,regexp" href="#tocamelcase">toCamelCase</a> <a class="sublink-1" tags="string,regexp" href="#tokebabcase">toKebabCase</a> <a class="sublink-1" tags="string,regexp" href="#tosnakecase">toSnakeCase</a> <a class="sublink-1" tags="string" href="#truncatestring">truncateString</a> <a class="sublink-1" tags="string,browser" href="#unescapehtml">unescapeHTML</a> <a class="sublink-1" tags="string,regexp" href="#words">words</a><h3>Type</h3><a class="sublink-1" tags="type" href="#gettype">getType</a> <a class="sublink-1" tags="type,array" href="#isarray">isArray</a> <a class="sublink-1" tags="type,array" href="#isarraylike">isArrayLike</a> <a class="sublink-1" tags="type" href="#isboolean">isBoolean</a> <a class="sublink-1" tags="type,function" href="#isfunction">isFunction</a> <a class="sublink-1" tags="type" href="#isnull">isNull</a> <a class="sublink-1" tags="type,math" href="#isnumber">isNumber</a> <a class="sublink-1" tags="type,object" href="#isobject">isObject</a> <a class="sublink-1" tags="type,function,array,string" href="#isprimitive">isPrimitive</a> <a class="sublink-1" tags="type,function,promise" href="#ispromiselike">isPromiseLike</a> <a class="sublink-1" tags="type,string" href="#isstring">isString</a> <a class="sublink-1" tags="type" href="#issymbol">isSymbol</a> <a class="sublink-1" tags="type,json" href="#isvalidjson">isValidJSON</a><h3>Utility</h3><a class="sublink-1" tags="utility,regexp" href="#cloneregexp">cloneRegExp</a> <a class="sublink-1" tags="utility" href="#coalesce">coalesce</a> <a class="sublink-1" tags="utility" href="#coalescefactory">coalesceFactory</a> <a class="sublink-1" tags="utility,string" href="#extendhex">extendHex</a> <a class="sublink-1" tags="utility,browser,string,url" href="#geturlparameters">getURLParameters</a> <a class="sublink-1" tags="utility,string,math,advanced" href="#hextorgb">hexToRGB</a> <a class="sublink-1" tags="utility,url,browser" href="#httpget">httpGet</a> <a class="sublink-1" tags="utility,url,browser" href="#httppost">httpPost</a> <a class="sublink-1" tags="utility,string,math" href="#prettybytes">prettyBytes</a> <a class="sublink-1" tags="utility,random" href="#randomhexcolorcode">randomHexColorCode</a> <a class="sublink-1" tags="utility" href="#rgbtohex">RGBToHex</a> <a class="sublink-1" tags="utility" href="#timetaken">timeTaken</a> <a class="sublink-1" tags="utility,math" href="#todecimalmark">toDecimalMark</a> <a class="sublink-1" tags="utility,math" href="#toordinalsuffix">toOrdinalSuffix</a> <a class="sublink-1" tags="utility,math" href="#validatenumber">validateNumber</a> <a class="sublink-1" tags="utility,regexp" href="#yesno">yesNo</a></nav><main class="col-sm-12 col-md-8 col-lg-9" style="height:100%;overflow-y:auto;background:#eceef2;padding:0"><a id="top"> </a><h2 style="text-align:center">Adapter</h2><div class="card fluid"><h3 id="call" class="section double-padded">call</h3><div class="section double-padded"><p>Given a key and a set of arguments, call them when given a context. Primarily useful in composition.</p><p>Use a closure to call a stored key with stored arguments.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">call</span> <span class="token operator">=</span> <span class="token punctuation">(</span>key<span class="token punctuation">,</span> <span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> context <span class="token operator">=></span> context<span class="token punctuation">[</span>key<span class="token punctuation">](</span><span class="token operator">...</span>args<span class="token punctuation">);</span>
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</pre><label class="collapse">Show examples</label><pre class="language-js">Promise<span class="token punctuation">.</span><span class="token function">resolve</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">])
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.</span><span class="token function">then</span><span class="token punctuation">(</span><span class="token function">call</span><span class="token punctuation">(</span><span class="token string">'map'</span><span class="token punctuation">,</span> x <span class="token operator">=></span> <span class="token number">2</span> <span class="token operator">*</span> x<span class="token punctuation">))
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.</span><span class="token function">then</span><span class="token punctuation">(</span>console<span class="token punctuation">.</span>log<span class="token punctuation">);</span> <span class="token comment">//[ 2, 4, 6 ]</span>
|
||
<span class="token keyword">const</span> map <span class="token operator">=</span> call<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">,</span> <span class="token string">'map'</span><span class="token punctuation">);</span>
|
||
Promise<span class="token punctuation">.</span><span class="token function">resolve</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">])
|
||
.</span><span class="token function">then</span><span class="token punctuation">(</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> <span class="token number">2</span> <span class="token operator">*</span> x<span class="token punctuation">))
|
||
.</span><span class="token function">then</span><span class="token punctuation">(</span>console<span class="token punctuation">.</span>log<span class="token punctuation">);</span> <span class="token comment">//[ 2, 4, 6 ]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="collectinto" class="section double-padded">collectInto</h3><div class="section double-padded"><p>Changes a function that accepts an array into a variadic function.</p><p>Given a function, return a closure that collects all inputs into an array-accepting function.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">collectInto</span> <span class="token operator">=</span> fn <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">fn</span><span class="token punctuation">(</span>args<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> Pall <span class="token operator">=</span> <span class="token function">collectInto</span><span class="token punctuation">(</span>Promise<span class="token punctuation">.</span>all<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span>Promise<span class="token punctuation">));</span>
|
||
<span class="token keyword">let</span> p1 <span class="token operator">=</span> Promise<span class="token punctuation">.</span><span class="token function">resolve</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">let</span> p2 <span class="token operator">=</span> Promise<span class="token punctuation">.</span><span class="token function">resolve</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">let</span> p3 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Promise</span><span class="token punctuation">(</span>resolve <span class="token operator">=></span> <span class="token function">setTimeout</span><span class="token punctuation">(</span>resolve<span class="token punctuation">,</span> <span class="token number">2000</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">));</span>
|
||
<span class="token function">Pall</span><span class="token punctuation">(</span>p1<span class="token punctuation">,</span> p2<span class="token punctuation">,</span> p3<span class="token punctuation">).</span><span class="token function">then</span><span class="token punctuation">(</span>console<span class="token punctuation">.</span>log<span class="token punctuation">);</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="flip" class="section double-padded">flip</h3><div class="section double-padded"><p>Flip takes a function as an argument, then makes the first argument the last.</p><p>Return a closure that takes variadic inputs, and splices the last argument to make it the first argument before applying the rest.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">flip</span> <span class="token operator">=</span> fn <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">fn</span><span class="token punctuation">(</span>args<span class="token punctuation">.</span><span class="token function">pop</span><span class="token punctuation">(),</span> <span class="token operator">...</span>args<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">let</span> a <span class="token operator">=</span> <span class="token punctuation">{</span> name<span class="token punctuation">:</span> <span class="token string">'John Smith'</span> <span class="token punctuation">};</span>
|
||
<span class="token keyword">let</span> b <span class="token operator">=</span> <span class="token punctuation">{};</span>
|
||
<span class="token keyword">const</span> mergeFrom <span class="token operator">=</span> <span class="token function">flip</span><span class="token punctuation">(</span>Object<span class="token punctuation">.</span>assign<span class="token punctuation">);</span>
|
||
<span class="token keyword">let</span> mergePerson <span class="token operator">=</span> mergeFrom<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">,</span> a<span class="token punctuation">);</span>
|
||
<span class="token function">mergePerson</span><span class="token punctuation">(</span>b<span class="token punctuation">);</span> <span class="token comment">// == b</span>
|
||
b <span class="token operator">=</span> <span class="token punctuation">{};</span>
|
||
Object<span class="token punctuation">.</span><span class="token function">assign</span><span class="token punctuation">(</span>b<span class="token punctuation">,</span> a<span class="token punctuation">);</span> <span class="token comment">// == b</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="pipefunctions" class="section double-padded">pipeFunctions</h3><div class="section double-padded"><p>Performs left-to-right function composition.</p><p>Use <code>Array.reduce()</code> with the spread operator (<code>...</code>) to perform left-to-right function composition. The first (leftmost) function can accept one or more arguments; the remaining functions must be unary.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">pipeFunctions</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>fns<span class="token punctuation">)</span> <span class="token operator">=></span> fns<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>f<span class="token punctuation">,</span> g<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">g</span><span class="token punctuation">(</span><span class="token function">f</span><span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">add5</span> <span class="token operator">=</span> x <span class="token operator">=></span> x <span class="token operator">+</span> <span class="token number">5</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">multiply</span> <span class="token operator">=</span> <span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">)</span> <span class="token operator">=></span> x <span class="token operator">*</span> y<span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> multiplyAndAdd5 <span class="token operator">=</span> <span class="token function">pipeFunctions</span><span class="token punctuation">(</span>multiply<span class="token punctuation">,</span> add5<span class="token punctuation">);</span>
|
||
<span class="token function">multiplyAndAdd5</span><span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// 15</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="promisify" class="section double-padded">promisify</h3><div class="section double-padded"><p>Converts an asynchronous function to return a promise.</p><p>Use currying to return a function returning a <code>Promise</code> that calls the original function. Use the <code>...rest</code> operator to pass in all the parameters.</p><p><em>In Node 8+, you can use <a href="https://nodejs.org/api/util.html#util_util_promisify_original"><code>util.promisify</code></a></em></p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">promisify</span> <span class="token operator">=</span> func <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token keyword">new</span> <span class="token class-name">Promise</span><span class="token punctuation">((</span>resolve<span class="token punctuation">,</span> reject<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token function">func</span><span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">, (</span>err<span class="token punctuation">,</span> result<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>err <span class="token operator">?</span> <span class="token function">reject</span><span class="token punctuation">(</span>err<span class="token punctuation">) :</span> <span class="token function">resolve</span><span class="token punctuation">(</span>result<span class="token punctuation">)))
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> delay <span class="token operator">=</span> <span class="token function">promisify</span><span class="token punctuation">((</span>d<span class="token punctuation">,</span> cb<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">setTimeout</span><span class="token punctuation">(</span>cb<span class="token punctuation">,</span> d<span class="token punctuation">));</span>
|
||
<span class="token function">delay</span><span class="token punctuation">(</span><span class="token number">2000</span><span class="token punctuation">).</span><span class="token function">then</span><span class="token punctuation">(()</span> <span class="token operator">=></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'Hi!'</span><span class="token punctuation">));</span> <span class="token comment">// // Promise resolves after 2s</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="spreadover" class="section double-padded">spreadOver</h3><div class="section double-padded"><p>Takes a variadic function and returns a closure that accepts an array of arguments to map to the inputs of the function.</p><p>Use closures and the spread operator (<code>...</code>) to map the array of arguments to the inputs of the function.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">spreadOver</span> <span class="token operator">=</span> fn <span class="token operator">=></span> argsArr <span class="token operator">=></span> <span class="token function">fn</span><span class="token punctuation">(</span><span class="token operator">...</span>argsArr<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> arrayMax <span class="token operator">=</span> <span class="token function">spreadOver</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span>max<span class="token punctuation">);</span>
|
||
<span class="token function">arrayMax</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// 3</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Array</h2><div class="card fluid"><h3 id="chunk" class="section double-padded">chunk</h3><div class="section double-padded"><p>Chunks an array into smaller arrays of a specified size.</p><p>Use <code>Array.from()</code> to create a new array, that fits the number of chunks that will be produced. Use <code>Array.slice()</code> to map each element of the new array to a chunk the length of <code>size</code>. If the original array can't be split evenly, the final chunk will contain the remaining elements.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">chunk</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> size<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">ceil</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length <span class="token operator">/</span> size<span class="token punctuation">) }, (</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>i <span class="token operator">*</span> size<span class="token punctuation">,</span> i <span class="token operator">*</span> size <span class="token operator">+</span> size<span class="token punctuation">)
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">chunk</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [[1,2],[3,4],[5]]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="compact" class="section double-padded">compact</h3><div class="section double-padded"><p>Removes falsey values from an array.</p><p>Use <code>Array.filter()</code> to filter out falsey values (<code>false</code>, <code>null</code>, <code>0</code>, <code>""</code>, <code>undefined</code>, and <code>NaN</code>).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">compact</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>Boolean<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">compact</span><span class="token punctuation">([</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token boolean">false</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token string">''</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'e'</span> <span class="token operator">*</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">NaN</span><span class="token punctuation">,</span> <span class="token string">'s'</span><span class="token punctuation">,</span> <span class="token number">34</span><span class="token punctuation">]);</span> <span class="token comment">// [ 1, 2, 3, 'a', 's', 34 ]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="countby" class="section double-padded">countBy</h3><div class="section double-padded"><p>Groups the elements of an array based on the given function and returns the count of elements in each group.</p><p>Use <code>Array.map()</code> to map the values of an array to a function or property name. Use <code>Array.reduce()</code> to create an object, where the keys are produced from the mapped results.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">countBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> fn <span class="token operator">===</span> <span class="token string">'function'</span> <span class="token operator">?</span> fn <span class="token punctuation">:</span> val <span class="token operator">=></span> val<span class="token punctuation">[</span>fn<span class="token punctuation">]).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span>val<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">(</span>acc<span class="token punctuation">[</span>val<span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">countBy</span><span class="token punctuation">([</span><span class="token number">6.1</span><span class="token punctuation">,</span> <span class="token number">4.2</span><span class="token punctuation">,</span> <span class="token number">6.3</span><span class="token punctuation">],</span> Math<span class="token punctuation">.</span>floor<span class="token punctuation">);</span> <span class="token comment">// {4: 1, 6: 2}</span>
|
||
<span class="token function">countBy</span><span class="token punctuation">([</span><span class="token string">'one'</span><span class="token punctuation">,</span> <span class="token string">'two'</span><span class="token punctuation">,</span> <span class="token string">'three'</span><span class="token punctuation">],</span> <span class="token string">'length'</span><span class="token punctuation">);</span> <span class="token comment">// {3: 2, 5: 1}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="countoccurrences" class="section double-padded">countOccurrences</h3><div class="section double-padded"><p>Counts the occurrences of a value in an array.</p><p>Use <code>Array.reduce()</code> to increment a counter each time you encounter the specific value inside the array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">countOccurrences</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>v <span class="token operator">===</span> val <span class="token operator">?</span> a <span class="token operator">+</span> <span class="token number">1</span> <span class="token punctuation">:</span> a <span class="token operator">+</span> <span class="token number">0</span><span class="token punctuation">),</span> <span class="token number">0</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">countOccurrences</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// 3</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="deepflatten" class="section double-padded">deepFlatten</h3><div class="section double-padded"><p>Deep flattens an array.</p><p>Use recursion. Use <code>Array.concat()</code> with an empty array (<code>[]</code>) and the spread operator (<code>...</code>) to flatten an array. Recursively flatten each element that is an array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">deepFlatten</span> <span class="token operator">=</span> arr <span class="token operator">=></span> <span class="token punctuation">[].</span><span class="token function">concat</span><span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>v <span class="token operator">=></span> <span class="token punctuation">(</span>Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token function">deepFlatten</span><span class="token punctuation">(</span>v<span class="token punctuation">) :</span> v<span class="token punctuation">)));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">deepFlatten</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">, [</span><span class="token number">2</span><span class="token punctuation">], [[</span><span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">4</span><span class="token punctuation">],</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// [1,2,3,4,5]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="difference" class="section double-padded">difference</h3><div class="section double-padded"><p>Returns the difference between two arrays.</p><p>Create a <code>Set</code> from <code>b</code>, then use <code>Array.filter()</code> on <code>a</code> to only keep values not contained in <code>b</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">difference</span> <span class="token operator">=</span> <span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> s <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>b<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> a<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>x <span class="token operator">=> !</span>s<span class="token punctuation">.</span><span class="token function">has</span><span class="token punctuation">(</span>x<span class="token punctuation">));
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">difference</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]);</span> <span class="token comment">// [3]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="differencewith" class="section double-padded">differenceWith</h3><div class="section double-padded"><p>Filters out all values from an array for which the comparator function does not return <code>true</code>.</p><p>Use <code>Array.filter()</code> and <code>Array.findIndex()</code> to find the appropriate values.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">differenceWith</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> val<span class="token punctuation">,</span> comp<span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>a <span class="token operator">=></span> val<span class="token punctuation">.</span><span class="token function">findIndex</span><span class="token punctuation">(</span>b <span class="token operator">=></span> <span class="token function">comp</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">))</span> <span class="token operator">=== -</span><span class="token number">1</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">differenceWith</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">1.2</span><span class="token punctuation">,</span> <span class="token number">1.5</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">], [</span><span class="token number">1.9</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">], (</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">round</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token operator">===</span> Math<span class="token punctuation">.</span><span class="token function">round</span><span class="token punctuation">(</span>b<span class="token punctuation">));</span> <span class="token comment">// [1, 1.2]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="distinctvaluesofarray" class="section double-padded">distinctValuesOfArray</h3><div class="section double-padded"><p>Returns all the distinct values of an array.</p><p>Use ES6 <code>Set</code> and the <code>...rest</code> operator to discard all duplicated values.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">distinctValuesOfArray</span> <span class="token operator">=</span> arr <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span><span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>arr<span class="token punctuation">)];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">distinctValuesOfArray</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// [1,2,3,4,5]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="dropelements" class="section double-padded">dropElements</h3><div class="section double-padded"><p>Removes elements in an array until the passed function returns <code>true</code>. Returns the remaining elements in the array.</p><p>Loop through the array, using <code>Array.slice()</code> to drop the first element of the array until the returned value from the function is <code>true</code>. Returns the remaining elements.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">dropElements</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> func<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">while</span> <span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">&& !</span><span class="token function">func</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]))</span> arr <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> arr<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">dropElements</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">],</span> n <span class="token operator">=></span> n <span class="token operator">>=</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// [3,4]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="dropright" class="section double-padded">dropRight</h3><div class="section double-padded"><p>Returns a new array with <code>n</code> elements removed from the right.</p><p>Use <code>Array.slice()</code> to slice the remove the specified number of elements from the right.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">dropRight</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token operator">-</span>n<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">dropRight</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// [1,2]</span>
|
||
<span class="token function">dropRight</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [1]</span>
|
||
<span class="token function">dropRight</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">42</span><span class="token punctuation">);</span> <span class="token comment">// []</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="everynth" class="section double-padded">everyNth</h3><div class="section double-padded"><p>Returns every nth element in an array.</p><p>Use <code>Array.filter()</code> to create a new array that contains every nth element of a given array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">everyNth</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> nth<span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">((</span>e<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> i <span class="token operator">%</span> nth <span class="token operator">===</span> nth <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">everyNth</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [ 2, 4, 6 ]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="filternonunique" class="section double-padded">filterNonUnique</h3><div class="section double-padded"><p>Filters out the non-unique values in an array.</p><p>Use <code>Array.filter()</code> for an array containing only the unique values.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">filterNonUnique</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>i <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span> <span class="token operator">===</span> arr<span class="token punctuation">.</span><span class="token function">lastIndexOf</span><span class="token punctuation">(</span>i<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">filterNonUnique</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// [1,3,5]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="findlast" class="section double-padded">findLast</h3><div class="section double-padded"><p>Returns the last element for which the provided function returns a truthy value.</p><p>Use <code>Array.filter()</code> to remove elements for which <code>fn</code> returns falsey values, <code>Array.slice(-1)</code> to get the last one.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">findLast</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>fn<span class="token punctuation">).</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">findLast</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">],</span> n <span class="token operator">=></span> n <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">===</span> <span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// 3</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="flatten" class="section double-padded">flatten</h3><div class="section double-padded"><p>Flattens an array up to the specified depth.</p><p>Use recursion, decrementing <code>depth</code> by 1 for each level of depth. Use <code>Array.reduce()</code> and <code>Array.concat()</code> to merge elements or arrays. Base case, for <code>depth</code> equal to <code>1</code> stops recursion. Omit the second argument, <code>depth</code> to flatten only to a depth of <code>1</code> (single flatten).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">flatten</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> depth <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
depth <span class="token operator">!=</span> <span class="token number">1</span>
|
||
<span class="token operator">?</span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> a<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token function">flatten</span><span class="token punctuation">(</span>v<span class="token punctuation">,</span> depth <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">) :</span> v<span class="token punctuation">), [])
|
||
:</span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> a<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>v<span class="token punctuation">), []);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">flatten</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">, [</span><span class="token number">2</span><span class="token punctuation">],</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]);</span> <span class="token comment">// [1, 2, 3, 4]</span>
|
||
<span class="token function">flatten</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">, [</span><span class="token number">2</span><span class="token punctuation">, [</span><span class="token number">3</span><span class="token punctuation">, [</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">],</span> <span class="token number">6</span><span class="token punctuation">],</span> <span class="token number">7</span><span class="token punctuation">],</span> <span class="token number">8</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [1, 2, 3, [4, 5], 6, 7, 8]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="foreachright" class="section double-padded">forEachRight</h3><div class="section double-padded"><p>Executes a provided function once for each array element, starting from the array's last element.</p><p>Use <code>Array.slice(0)</code> to clone the given array, <code>Array.reverse()</code> to reverse it and <code>Array.forEach()</code> to iterate over the reversed array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">forEachRight</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> callback<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr
|
||
<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)
|
||
.</span><span class="token function">reverse</span><span class="token punctuation">()
|
||
.</span><span class="token function">forEach</span><span class="token punctuation">(</span>callback<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">forEachRight</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">],</span> val <span class="token operator">=></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>val<span class="token punctuation">));</span> <span class="token comment">// '4', '3', '2', '1'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="groupby" class="section double-padded">groupBy</h3><div class="section double-padded"><p>Groups the elements of an array based on the given function.</p><p>Use <code>Array.map()</code> to map the values of an array to a function or property name. Use <code>Array.reduce()</code> to create an object, where the keys are produced from the mapped results.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">groupBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> fn <span class="token operator">===</span> <span class="token string">'function'</span> <span class="token operator">?</span> fn <span class="token punctuation">:</span> val <span class="token operator">=></span> val<span class="token punctuation">[</span>fn<span class="token punctuation">]).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span>val<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">(</span>acc<span class="token punctuation">[</span>val<span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token punctuation">[]).</span><span class="token function">concat</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">]);</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">groupBy</span><span class="token punctuation">([</span><span class="token number">6.1</span><span class="token punctuation">,</span> <span class="token number">4.2</span><span class="token punctuation">,</span> <span class="token number">6.3</span><span class="token punctuation">],</span> Math<span class="token punctuation">.</span>floor<span class="token punctuation">);</span> <span class="token comment">// {4: [4.2], 6: [6.1, 6.3]}</span>
|
||
<span class="token function">groupBy</span><span class="token punctuation">([</span><span class="token string">'one'</span><span class="token punctuation">,</span> <span class="token string">'two'</span><span class="token punctuation">,</span> <span class="token string">'three'</span><span class="token punctuation">],</span> <span class="token string">'length'</span><span class="token punctuation">);</span> <span class="token comment">// {3: ['one', 'two'], 5: ['three']}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="head" class="section double-padded">head</h3><div class="section double-padded"><p>Returns the head of a list.</p><p>Use <code>arr[0]</code> to return the first element of the passed array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">head</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">head</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// 1</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="indexofall" class="section double-padded">indexOfAll</h3><div class="section double-padded"><p>Returns all indices of <code>val</code> in an array. If <code>val</code> never occurs, returns <code>[]</code>.</p><p>Use <code>Array.forEach()</code> to loop over elements and <code>Array.push()</code> to store indices for matching elements. Return the array of indices.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">indexOfAll</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> indices <span class="token operator">=</span> <span class="token punctuation">[];</span>
|
||
arr<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">((</span>el<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> el <span class="token operator">===</span> val <span class="token operator">&&</span> indices<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>i<span class="token punctuation">));</span>
|
||
<span class="token keyword">return</span> indices<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">indexOfAll</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// [0,3]</span>
|
||
<span class="token function">indexOfAll</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">4</span><span class="token punctuation">);</span> <span class="token comment">// []</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="initial" class="section double-padded">initial</h3><div class="section double-padded"><p>Returns all the elements of an array except the last one.</p><p>Use <code>arr.slice(0,-1)</code> to return all but the last element of the array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">initial</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">);</span>
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||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">initial</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// [1,2]</span>
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||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="initialize2darray" class="section double-padded">initialize2DArray</h3><div class="section double-padded"><p>Initializes a 2D array of given width and height and value.</p><p>Use <code>Array.map()</code> to generate h rows where each is a new array of size w initialize with value. If the value is not provided, default to <code>null</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">initialize2DArray</span> <span class="token operator">=</span> <span class="token punctuation">(</span>w<span class="token punctuation">,</span> h<span class="token punctuation">,</span> val <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token operator">=></span>
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||
Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> h <span class="token punctuation">}).</span><span class="token function">map</span><span class="token punctuation">(()</span> <span class="token operator">=></span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> w <span class="token punctuation">}).</span><span class="token function">fill</span><span class="token punctuation">(</span>val<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">initialize2DArray</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">);</span> <span class="token comment">// [[0,0], [0,0]]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="initializearraywithrange" class="section double-padded">initializeArrayWithRange</h3><div class="section double-padded"><p>Initializes an array containing the numbers in the specified range where <code>start</code> and <code>end</code> are inclusive with there common difference <code>step</code>.</p><p>Use <code>Array.from(Math.ceil((end+1-start)/step))</code> to create an array of the desired length(the amounts of elements is equal to <code>(end-start)/step</code> or <code>(end+1-start)/step</code> for inclusive end), <code>Array.map()</code> to fill with the desired values in a range. You can omit <code>start</code> to use a default value of <code>0</code>. You can omit <code>step</code> to use a default value of <code>1</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">initializeArrayWithRange</span> <span class="token operator">=</span> <span class="token punctuation">(</span>end<span class="token punctuation">,</span> start <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> step <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span>
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||
Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">ceil</span><span class="token punctuation">((</span>end <span class="token operator">+</span> <span class="token number">1</span> <span class="token operator">-</span> start<span class="token punctuation">)</span> <span class="token operator">/</span> step<span class="token punctuation">) }).</span><span class="token function">map</span><span class="token punctuation">((</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> i <span class="token operator">*</span> step <span class="token operator">+</span> start<span class="token punctuation">);</span>
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||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">initializeArrayWithRange</span><span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// [0,1,2,3,4,5]</span>
|
||
<span class="token function">initializeArrayWithRange</span><span class="token punctuation">(</span><span class="token number">7</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// [3,4,5,6,7]</span>
|
||
<span class="token function">initializeArrayWithRange</span><span class="token punctuation">(</span><span class="token number">9</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [0,2,4,6,8]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="initializearraywithvalues" class="section double-padded">initializeArrayWithValues</h3><div class="section double-padded"><p>Initializes and fills an array with the specified values.</p><p>Use <code>Array(n)</code> to create an array of the desired length, <code>fill(v)</code> to fill it with the desired values. You can omit <code>val</code> to use a default value of <code>0</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">initializeArrayWithValues</span> <span class="token operator">=</span> <span class="token punctuation">(</span>n<span class="token punctuation">,</span> val <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">Array</span><span class="token punctuation">(</span>n<span class="token punctuation">).</span><span class="token function">fill</span><span class="token punctuation">(</span>val<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">initializeArrayWithValues</span><span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [2,2,2,2,2]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="intersection" class="section double-padded">intersection</h3><div class="section double-padded"><p>Returns a list of elements that exist in both arrays.</p><p>Create a <code>Set</code> from <code>b</code>, then use <code>Array.filter()</code> on <code>a</code> to only keep values contained in <code>b</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">intersection</span> <span class="token operator">=</span> <span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> s <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>b<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> a<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>x <span class="token operator">=></span> s<span class="token punctuation">.</span><span class="token function">has</span><span class="token punctuation">(</span>x<span class="token punctuation">));
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">intersection</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">], [</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]);</span> <span class="token comment">// [2,3]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="issorted" class="section double-padded">isSorted</h3><div class="section double-padded"><p>Returns <code>1</code> if the array is sorted in ascending order, <code>-1</code> if it is sorted in descending order or <code>0</code> if it is not sorted.</p><p>Calculate the ordering <code>direction</code> for the first two elements. Use <code>Object.entries()</code> to loop over array objects and compare them in pairs. Return <code>0</code> if the <code>direction</code> changes or the <code>direction</code> if the last element is reached.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isSorted</span> <span class="token operator">=</span> arr <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> direction <span class="token operator">=</span> arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">></span> arr<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">? -</span><span class="token number">1</span> <span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> <span class="token punctuation">[</span>i<span class="token punctuation">,</span> val<span class="token punctuation">]</span> <span class="token keyword">of</span> arr<span class="token punctuation">.</span><span class="token function">entries</span><span class="token punctuation">())</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>i <span class="token operator">===</span> arr<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">return</span> direction<span class="token punctuation">;</span>
|
||
<span class="token keyword">else if</span> <span class="token punctuation">((</span>val <span class="token operator">-</span> arr<span class="token punctuation">[</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">])</span> <span class="token operator">*</span> direction <span class="token operator">></span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isSorted</span><span class="token punctuation">([</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]);</span> <span class="token comment">// 1</span>
|
||
<span class="token function">isSorted</span><span class="token punctuation">([</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]);</span> <span class="token comment">// -1</span>
|
||
<span class="token function">isSorted</span><span class="token punctuation">([</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// 0</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="join" class="section double-padded">join</h3><div class="section double-padded"><p>Joins all elements of an array into a string and returns this string. Uses a separator and an end separator.</p><p>Use <code>Array.reduce()</code> to combine elements into a string. Omit the second argument, <code>separator</code>, to use a default separator of <code>','</code>. Omit the third argument, <code>end</code>, to use the same value as <code>separator</code> by default.</p><pre class="language-js"><span class="token keyword">const</span> join <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> separator <span class="token operator">=</span> <span class="token string">','</span><span class="token punctuation">,</span> end <span class="token operator">=</span> separator<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(
|
||
(</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
i <span class="token operator">==</span> arr<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">2</span>
|
||
<span class="token operator">?</span> acc <span class="token operator">+</span> val <span class="token operator">+</span> end
|
||
<span class="token punctuation">:</span> i <span class="token operator">==</span> arr<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span> <span class="token operator">?</span> acc <span class="token operator">+</span> val <span class="token punctuation">:</span> acc <span class="token operator">+</span> val <span class="token operator">+</span> separator<span class="token punctuation">,</span>
|
||
<span class="token string">''</span>
|
||
<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">join</span><span class="token punctuation">([</span><span class="token string">'pen'</span><span class="token punctuation">,</span> <span class="token string">'pineapple'</span><span class="token punctuation">,</span> <span class="token string">'apple'</span><span class="token punctuation">,</span> <span class="token string">'pen'</span><span class="token punctuation">],</span> <span class="token string">','</span><span class="token punctuation">,</span> <span class="token string">'&'</span><span class="token punctuation">);</span> <span class="token comment">// "pen,pineapple,apple&pen"</span>
|
||
<span class="token function">join</span><span class="token punctuation">([</span><span class="token string">'pen'</span><span class="token punctuation">,</span> <span class="token string">'pineapple'</span><span class="token punctuation">,</span> <span class="token string">'apple'</span><span class="token punctuation">,</span> <span class="token string">'pen'</span><span class="token punctuation">],</span> <span class="token string">','</span><span class="token punctuation">);</span> <span class="token comment">// "pen,pineapple,apple,pen"</span>
|
||
<span class="token function">join</span><span class="token punctuation">([</span><span class="token string">'pen'</span><span class="token punctuation">,</span> <span class="token string">'pineapple'</span><span class="token punctuation">,</span> <span class="token string">'apple'</span><span class="token punctuation">,</span> <span class="token string">'pen'</span><span class="token punctuation">]);</span> <span class="token comment">// "pen,pineapple,apple,pen"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="last" class="section double-padded">last</h3><div class="section double-padded"><p>Returns the last element in an array.</p><p>Use <code>arr.length - 1</code> to compute the index of the last element of the given array and returning it.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">last</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">[</span>arr<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">last</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// 3</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="longestitem" class="section double-padded">longestItem</h3><div class="section double-padded"><p>Takes any number of iterable objects or objects with a <code>length</code> property and returns the longest one.</p><p>Use <code>Array.sort()</code> to sort all arguments by <code>length</code>, return the first (longest) one.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">longestItem</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>vals<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>vals<span class="token punctuation">].</span><span class="token function">sort</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> b<span class="token punctuation">.</span>length <span class="token operator">-</span> a<span class="token punctuation">.</span>length<span class="token punctuation">)[</span><span class="token number">0</span><span class="token punctuation">];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">longestItem</span><span class="token punctuation">(</span><span class="token string">'this'</span><span class="token punctuation">,</span> <span class="token string">'is'</span><span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'testcase'</span><span class="token punctuation">);</span> <span class="token comment">// 'testcase'</span>
|
||
<span class="token function">longestItem</span><span class="token punctuation">(</span><span class="token operator">...</span><span class="token punctuation">[</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'ab'</span><span class="token punctuation">,</span> <span class="token string">'abc'</span><span class="token punctuation">]);</span> <span class="token comment">// 'abc'</span>
|
||
<span class="token function">longestItem</span><span class="token punctuation">(</span><span class="token operator">...</span><span class="token punctuation">[</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'ab'</span><span class="token punctuation">,</span> <span class="token string">'abc'</span><span class="token punctuation">],</span> <span class="token string">'abcd'</span><span class="token punctuation">);</span> <span class="token comment">// 'abcd'</span>
|
||
<span class="token function">longestItem</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// [1, 2, 3, 4, 5]</span>
|
||
<span class="token function">longestItem</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token string">'foobar'</span><span class="token punctuation">);</span> <span class="token comment">// 'foobar'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="mapobject" class="section double-padded">mapObject</h3><div class="section double-padded"><p>Maps the values of an array to an object using a function, where the key-value pairs consist of the original value as the key and the mapped value.</p><p>Use an anonymous inner function scope to declare an undefined memory space, using closures to store a return value. Use a new <code>Array</code> to store the array with a map of the function over its data set and a comma operator to return a second step, without needing to move from one context to another (due to closures and order of operations).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">mapObject</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span>a <span class="token operator">=></span> <span class="token punctuation">(
|
||
(</span>a <span class="token operator">=</span> <span class="token punctuation">[</span>arr<span class="token punctuation">,</span> arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>fn<span class="token punctuation">)]),</span> a<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">].</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">,</span> ind<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">((</span>acc<span class="token punctuation">[</span>val<span class="token punctuation">]</span> <span class="token operator">=</span> a<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">][</span>ind<span class="token punctuation">]),</span> acc<span class="token punctuation">), {})
|
||
))();</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">squareIt</span> <span class="token operator">=</span> arr <span class="token operator">=></span> <span class="token function">mapObject</span><span class="token punctuation">(</span>arr<span class="token punctuation">,</span> a <span class="token operator">=></span> a <span class="token operator">*</span> a<span class="token punctuation">);</span>
|
||
<span class="token function">squareIt</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// { 1: 1, 2: 4, 3: 9 }</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="maxn" class="section double-padded">maxN</h3><div class="section double-padded"><p>Returns the <code>n</code> maximum elements from the provided array. If <code>n</code> is greater than or equal to the provided array's length, then return the original array(sorted in descending order).</p><p>Use <code>Array.sort()</code> combined with the spread operator (<code>...</code>) to create a shallow clone of the array and sort it in descending order. Use <code>Array.slice()</code> to get the specified number of elements. Omit the second argument, <code>n</code>, to get a one-element array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">maxN</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">sort</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> b <span class="token operator">-</span> a<span class="token punctuation">).</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> n<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">maxN</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// [3]</span>
|
||
<span class="token function">maxN</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [3,2]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="minn" class="section double-padded">minN</h3><div class="section double-padded"><p>Returns the <code>n</code> minimum elements from the provided array. If <code>n</code> is greater than or equal to the provided array's length, then return the original array(sorted in ascending order).</p><p>Use <code>Array.sort()</code> combined with the spread operator (<code>...</code>) to create a shallow clone of the array and sort it in ascending order. Use <code>Array.slice()</code> to get the specified number of elements. Omit the second argument, <code>n</code>, to get a one-element array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">minN</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">sort</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> a <span class="token operator">-</span> b<span class="token punctuation">).</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> n<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">minN</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// [1]</span>
|
||
<span class="token function">minN</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [1,2]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="nthelement" class="section double-padded">nthElement</h3><div class="section double-padded"><p>Returns the nth element of an array.</p><p>Use <code>Array.slice()</code> to get an array containing the nth element at the first place. If the index is out of bounds, return <code>[]</code>. Omit the second argument, <code>n</code>, to get the first element of the array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">nthElement</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>n <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">?</span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>n<span class="token punctuation">,</span> n <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">) :</span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>n<span class="token punctuation">))[</span><span class="token number">0</span><span class="token punctuation">];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">nthElement</span><span class="token punctuation">([</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">],</span> <span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// 'b'</span>
|
||
<span class="token function">nthElement</span><span class="token punctuation">([</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">],</span> <span class="token operator">-</span><span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// 'a'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="partition" class="section double-padded">partition</h3><div class="section double-padded"><p>Groups the elements into two arrays, depending on the provided function's truthiness for each element.</p><p>Use <code>Array.reduce()</code> to create an array of two arrays. Use <code>Array.push()</code> to add elements for which <code>fn</code> returns <code>true</code> to the first array and elements for which <code>fn</code> returns <code>false</code> to the second one.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">partition</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(
|
||
(</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">,</span> i<span class="token punctuation">,</span> arr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span><span class="token function">fn</span><span class="token punctuation">(</span>val<span class="token punctuation">,</span> i<span class="token punctuation">,</span> arr<span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token number">0</span> <span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">].</span><span class="token function">push</span><span class="token punctuation">(</span>val<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
},
|
||
[[], []]
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> users <span class="token operator">=</span> <span class="token punctuation">[{</span> user<span class="token punctuation">:</span> <span class="token string">'barney'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">36</span><span class="token punctuation">,</span> active<span class="token punctuation">:</span> <span class="token boolean">false</span> <span class="token punctuation">}, {</span> user<span class="token punctuation">:</span> <span class="token string">'fred'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">40</span><span class="token punctuation">,</span> active<span class="token punctuation">:</span> <span class="token boolean">true</span> <span class="token punctuation">}];</span>
|
||
<span class="token function">partition</span><span class="token punctuation">(</span>users<span class="token punctuation">,</span> o <span class="token operator">=></span> o<span class="token punctuation">.</span>active<span class="token punctuation">);</span> <span class="token comment">// [[{ 'user': 'fred', 'age': 40, 'active': true }],[{ 'user': 'barney', 'age': 36, 'active': false }]]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="pick" class="section double-padded">pick</h3><div class="section double-padded"><p>Picks the key-value pairs corresponding to the given keys from an object.</p><p>Use <code>Array.reduce()</code> to convert the filtered/picked keys back to an object with the corresponding key-value pair if the key exists in the obj.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">pick</span> <span class="token operator">=</span> <span class="token punctuation">(</span>obj<span class="token punctuation">,</span> arr<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> curr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>curr <span class="token keyword">in</span> obj <span class="token operator">&&</span> <span class="token punctuation">(</span>acc<span class="token punctuation">[</span>curr<span class="token punctuation">]</span> <span class="token operator">=</span> obj<span class="token punctuation">[</span>curr<span class="token punctuation">]),</span> acc<span class="token punctuation">), {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">pick</span><span class="token punctuation">({</span> a<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token punctuation">:</span> <span class="token string">'2'</span><span class="token punctuation">,</span> c<span class="token punctuation">:</span> <span class="token number">3</span> <span class="token punctuation">}, [</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">]);</span> <span class="token comment">// { 'a': 1, 'c': 3 }</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="pull" class="section double-padded">pull</h3><div class="section double-padded"><p>Mutates the original array to filter out the values specified.</p><p>Use <code>Array.filter()</code> and <code>Array.includes()</code> to pull out the values that are not needed. Use <code>Array.length = 0</code> to mutate the passed in an array by resetting it's length to zero and <code>Array.push()</code> to re-populate it with only the pulled values.</p><p><em>(For a snippet that does not mutate the original array see <a href="#without"><code>without</code></a>)</em></p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">pull</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> <span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> argState <span class="token operator">=</span> Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>args<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">])</span> <span class="token operator">?</span> args<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">] :</span> args<span class="token punctuation">;</span>
|
||
<span class="token keyword">let</span> pulled <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">((</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=> !</span>argState<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>v<span class="token punctuation">));</span>
|
||
arr<span class="token punctuation">.</span>length <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
pulled<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>v <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>v<span class="token punctuation">));
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">let</span> myArray <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">];</span>
|
||
<span class="token function">pull</span><span class="token punctuation">(</span>myArray<span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">);</span> <span class="token comment">// myArray = [ 'b', 'b' ]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="pullatindex" class="section double-padded">pullAtIndex</h3><div class="section double-padded"><p>Mutates the original array to filter out the values at the specified indexes.</p><p>Use <code>Array.filter()</code> and <code>Array.includes()</code> to pull out the values that are not needed. Use <code>Array.length = 0</code> to mutate the passed in an array by resetting it's length to zero and <code>Array.push()</code> to re-populate it with only the pulled values. Use <code>Array.push()</code> to keep track of pulled values</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">pullAtIndex</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> pullArr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> removed <span class="token operator">=</span> <span class="token punctuation">[];</span>
|
||
<span class="token keyword">let</span> pulled <span class="token operator">=</span> arr
|
||
<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">((</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>pullArr<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span> <span class="token operator">?</span> removed<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>v<span class="token punctuation">) :</span> v<span class="token punctuation">))
|
||
.</span><span class="token function">filter</span><span class="token punctuation">((</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=> !</span>pullArr<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>i<span class="token punctuation">));</span>
|
||
arr<span class="token punctuation">.</span>length <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
pulled<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>v <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>v<span class="token punctuation">));</span>
|
||
<span class="token keyword">return</span> removed<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">let</span> myArray <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">,</span> <span class="token string">'d'</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">let</span> pulled <span class="token operator">=</span> <span class="token function">pullAtIndex</span><span class="token punctuation">(</span>myArray<span class="token punctuation">, [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// myArray = [ 'a', 'c' ] , pulled = [ 'b', 'd' ]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="pullatvalue" class="section double-padded">pullAtValue</h3><div class="section double-padded"><p>Mutates the original array to filter out the values specified. Returns the removed elements.</p><p>Use <code>Array.filter()</code> and <code>Array.includes()</code> to pull out the values that are not needed. Use <code>Array.length = 0</code> to mutate the passed in an array by resetting it's length to zero and <code>Array.push()</code> to re-populate it with only the pulled values. Use <code>Array.push()</code> to keep track of pulled values</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">pullAtValue</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> pullArr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> removed <span class="token operator">=</span> <span class="token punctuation">[],</span>
|
||
pushToRemove <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">((</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>pullArr<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span> <span class="token operator">?</span> removed<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>v<span class="token punctuation">) :</span> v<span class="token punctuation">)),</span>
|
||
mutateTo <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">((</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=> !</span>pullArr<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>v<span class="token punctuation">));</span>
|
||
arr<span class="token punctuation">.</span>length <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
mutateTo<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>v <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>v<span class="token punctuation">));</span>
|
||
<span class="token keyword">return</span> removed<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">let</span> myArray <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">,</span> <span class="token string">'d'</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">let</span> pulled <span class="token operator">=</span> <span class="token function">pullAtValue</span><span class="token punctuation">(</span>myArray<span class="token punctuation">, [</span><span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'d'</span><span class="token punctuation">]);</span> <span class="token comment">// myArray = [ 'a', 'c' ] , pulled = [ 'b', 'd' ]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="reducedfilter" class="section double-padded">reducedFilter</h3><div class="section double-padded"><p>Filter an array of objects based on a condition while also filtering out unspecified keys.</p><p>Use <code>Array.filter()</code> to filter the array based on the predicate <code>fn</code> so that it returns the objects for which the condition returned a truthy value. On the filtered array, use <code>Array.map()</code> to return the new object using <code>Array.reduce()</code> to filter out the keys which were not supplied as the <code>keys</code> argument.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">reducedFilter</span> <span class="token operator">=</span> <span class="token punctuation">(</span>data<span class="token punctuation">,</span> keys<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
data<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>fn<span class="token punctuation">).</span><span class="token function">map</span><span class="token punctuation">(</span>el <span class="token operator">=></span>
|
||
keys<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> key<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span>key<span class="token punctuation">]</span> <span class="token operator">=</span> el<span class="token punctuation">[</span>key<span class="token punctuation">];</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {})
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> data <span class="token operator">=</span> <span class="token punctuation">[
|
||
{</span>
|
||
id<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
|
||
name<span class="token punctuation">:</span> <span class="token string">'john'</span><span class="token punctuation">,</span>
|
||
age<span class="token punctuation">:</span> <span class="token number">24</span>
|
||
<span class="token punctuation">},
|
||
{</span>
|
||
id<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span>
|
||
name<span class="token punctuation">:</span> <span class="token string">'mike'</span><span class="token punctuation">,</span>
|
||
age<span class="token punctuation">:</span> <span class="token number">50</span>
|
||
<span class="token punctuation">}
|
||
];</span>
|
||
|
||
<span class="token function">reducedFilter</span><span class="token punctuation">(</span>data<span class="token punctuation">, [</span><span class="token string">'id'</span><span class="token punctuation">,</span> <span class="token string">'name'</span><span class="token punctuation">],</span> item <span class="token operator">=></span> item<span class="token punctuation">.</span>age <span class="token operator">></span> <span class="token number">24</span><span class="token punctuation">);</span> <span class="token comment">// [{ id: 2, name: 'mike'}]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="remove" class="section double-padded">remove</h3><div class="section double-padded"><p>Removes elements from an array for which the given function returns <code>false</code>.</p><p>Use <code>Array.filter()</code> to find array elements that return truthy values and <code>Array.reduce()</code> to remove elements using <code>Array.splice()</code>. The <code>func</code> is invoked with three arguments (<code>value, index, array</code>).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">remove</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> func<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span>
|
||
<span class="token operator">?</span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>func<span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
arr<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span>val<span class="token punctuation">),</span> <span class="token number">1</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>val<span class="token punctuation">);
|
||
}, [])
|
||
: [];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">remove</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">],</span> n <span class="token operator">=></span> n <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">);</span> <span class="token comment">// [2, 4]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sample" class="section double-padded">sample</h3><div class="section double-padded"><p>Returns a random element from an array.</p><p>Use <code>Math.random()</code> to generate a random number, multiply it by <code>length</code> and round it of to the nearest whole number using <code>Math.floor()</code>. This method also works with strings.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sample</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">[</span>Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">)];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sample</span><span class="token punctuation">([</span><span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">,</span> <span class="token number">9</span><span class="token punctuation">,</span> <span class="token number">11</span><span class="token punctuation">]);</span> <span class="token comment">// 9</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="samplesize" class="section double-padded">sampleSize</h3><div class="section double-padded"><p>Gets <code>n</code> random elements at unique keys from <code>array</code> up to the size of <code>array</code>.</p><p>Shuffle the array using the <a href="https://github.com/chalarangelo/30-seconds-of-code#shuffle">Fisher-Yates algorithm</a>. Use <code>Array.slice()</code> to get the first <code>n</code> elements. Omit the second argument, <code>n</code> to get only one element at random from the array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sampleSize</span> <span class="token operator">=</span> <span class="token punctuation">([</span><span class="token operator">...</span>arr<span class="token punctuation">],</span> n <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> m <span class="token operator">=</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
|
||
<span class="token keyword">while</span> <span class="token punctuation">(</span>m<span class="token punctuation">) {</span>
|
||
<span class="token keyword">const</span> i <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> m<span class="token operator">--</span><span class="token punctuation">);
|
||
[</span>arr<span class="token punctuation">[</span>m<span class="token punctuation">],</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]]</span> <span class="token operator">=</span> <span class="token punctuation">[</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">],</span> arr<span class="token punctuation">[</span>m<span class="token punctuation">]];
|
||
}</span>
|
||
<span class="token keyword">return</span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> n<span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sampleSize</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [3,1]</span>
|
||
<span class="token function">sampleSize</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">4</span><span class="token punctuation">);</span> <span class="token comment">// [2,3,1]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="shuffle" class="section double-padded">shuffle</h3><div class="section double-padded"><p>Randomizes the order of the values of an array, returning a new array.</p><p>Uses the <a href="https://github.com/chalarangelo/30-seconds-of-code#shuffle">Fisher-Yates algorithm</a> to reorder the elements of the array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">shuffle</span> <span class="token operator">=</span> <span class="token punctuation">([</span><span class="token operator">...</span>arr<span class="token punctuation">])</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> m <span class="token operator">=</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
|
||
<span class="token keyword">while</span> <span class="token punctuation">(</span>m<span class="token punctuation">) {</span>
|
||
<span class="token keyword">const</span> i <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> m<span class="token operator">--</span><span class="token punctuation">);
|
||
[</span>arr<span class="token punctuation">[</span>m<span class="token punctuation">],</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]]</span> <span class="token operator">=</span> <span class="token punctuation">[</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">],</span> arr<span class="token punctuation">[</span>m<span class="token punctuation">]];
|
||
}</span>
|
||
<span class="token keyword">return</span> arr<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> foo <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">];</span>
|
||
<span class="token function">shuffle</span><span class="token punctuation">(</span>foo<span class="token punctuation">);</span> <span class="token comment">// [2,3,1], foo = [1,2,3]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="similarity" class="section double-padded">similarity</h3><div class="section double-padded"><p>Returns an array of elements that appear in both arrays.</p><p>Use <code>Array.filter()</code> to remove values that are not part of <code>values</code>, determined using <code>Array.includes()</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">similarity</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> values<span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>v <span class="token operator">=></span> values<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>v<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">similarity</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]);</span> <span class="token comment">// [1,2]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sortedindex" class="section double-padded">sortedIndex</h3><div class="section double-padded"><p>Returns the lowest index at which value should be inserted into array in order to maintain its sort order.</p><p>Check if the array is sorted in descending order (loosely). Use <code>Array.findIndex()</code> to find the appropriate index where the element should be inserted.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sortedIndex</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> isDescending <span class="token operator">=</span> arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">></span> arr<span class="token punctuation">[</span>arr<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">const</span> index <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">findIndex</span><span class="token punctuation">(</span>el <span class="token operator">=></span> <span class="token punctuation">(</span>isDescending <span class="token operator">?</span> n <span class="token operator">>=</span> el <span class="token punctuation">:</span> n <span class="token operator"><=</span> el<span class="token punctuation">));</span>
|
||
<span class="token keyword">return</span> index <span class="token operator">=== -</span><span class="token number">1</span> <span class="token operator">?</span> arr<span class="token punctuation">.</span>length <span class="token punctuation">:</span> index<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sortedIndex</span><span class="token punctuation">([</span><span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">],</span> <span class="token number">4</span><span class="token punctuation">);</span> <span class="token comment">// 1</span>
|
||
<span class="token function">sortedIndex</span><span class="token punctuation">([</span><span class="token number">30</span><span class="token punctuation">,</span> <span class="token number">50</span><span class="token punctuation">],</span> <span class="token number">40</span><span class="token punctuation">);</span> <span class="token comment">// 1</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="symmetricdifference" class="section double-padded">symmetricDifference</h3><div class="section double-padded"><p>Returns the symmetric difference between two arrays.</p><p>Create a <code>Set</code> from each array, then use <code>Array.filter()</code> on each of them to only keep values not contained in the other.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">symmetricDifference</span> <span class="token operator">=</span> <span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> sA <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>a<span class="token punctuation">),</span>
|
||
sB <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>b<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token operator">...</span>a<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>x <span class="token operator">=> !</span>sB<span class="token punctuation">.</span><span class="token function">has</span><span class="token punctuation">(</span>x<span class="token punctuation">)),</span> <span class="token operator">...</span>b<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>x <span class="token operator">=> !</span>sA<span class="token punctuation">.</span><span class="token function">has</span><span class="token punctuation">(</span>x<span class="token punctuation">))];
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">symmetricDifference</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]);</span> <span class="token comment">// [3,4]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="tail" class="section double-padded">tail</h3><div class="section double-padded"><p>Returns all elements in an array except for the first one.</p><p>Return <code>Array.slice(1)</code> if the array's <code>length</code> is more than <code>1</code>, otherwise, return the whole array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">tail</span> <span class="token operator">=</span> arr <span class="token operator">=></span> <span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length <span class="token operator">></span> <span class="token number">1</span> <span class="token operator">?</span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">) :</span> arr<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">tail</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// [2,3]</span>
|
||
<span class="token function">tail</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">]);</span> <span class="token comment">// [1]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="take" class="section double-padded">take</h3><div class="section double-padded"><p>Returns an array with n elements removed from the beginning.</p><p>Use <code>Array.slice()</code> to create a slice of the array with <code>n</code> elements taken from the beginning.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">take</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> n<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">take</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// [1, 2, 3]</span>
|
||
<span class="token function">take</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">0</span><span class="token punctuation">);</span> <span class="token comment">// []</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="takeright" class="section double-padded">takeRight</h3><div class="section double-padded"><p>Returns an array with n elements removed from the end.</p><p>Use <code>Array.slice()</code> to create a slice of the array with <code>n</code> elements taken from the end.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">takeRight</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length <span class="token operator">-</span> n<span class="token punctuation">,</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">takeRight</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [ 2, 3 ]</span>
|
||
<span class="token function">takeRight</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// [3]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="union" class="section double-padded">union</h3><div class="section double-padded"><p>Returns every element that exists in any of the two arrays once.</p><p>Create a <code>Set</code> with all values of <code>a</code> and <code>b</code> and convert to an array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">union</span> <span class="token operator">=</span> <span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">([</span><span class="token operator">...</span>a<span class="token punctuation">,</span> <span class="token operator">...</span>b<span class="token punctuation">]));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">union</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">], [</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]);</span> <span class="token comment">// [1,2,3,4]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="without" class="section double-padded">without</h3><div class="section double-padded"><p>Filters out the elements of an array, that have one of the specified values.</p><p>Use <code>Array.filter()</code> to create an array excluding(using <code>!Array.includes()</code>) all given values.</p><p><em>(For a snippet that mutates the original array see <a href="#pull"><code>pull</code></a>)</em></p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">without</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> <span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>v <span class="token operator">=> !</span>args<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>v<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">without</span><span class="token punctuation">([</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// [3]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="zip" class="section double-padded">zip</h3><div class="section double-padded"><p>Creates an array of elements, grouped based on the position in the original arrays.</p><p>Use <code>Math.max.apply()</code> to get the longest array in the arguments. Creates an array with that length as return value and use <code>Array.from()</code> with a map-function to create an array of grouped elements. If lengths of the argument-arrays vary, <code>undefined</code> is used where no value could be found.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">zip</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>arrays<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> maxLength <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span><span class="token operator">...</span>arrays<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> x<span class="token punctuation">.</span>length<span class="token punctuation">));</span>
|
||
<span class="token keyword">return</span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> maxLength <span class="token punctuation">}).</span><span class="token function">map</span><span class="token punctuation">((</span>_<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">return</span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> arrays<span class="token punctuation">.</span>length <span class="token punctuation">}, (</span>_<span class="token punctuation">,</span> k<span class="token punctuation">)</span> <span class="token operator">=></span> arrays<span class="token punctuation">[</span>k<span class="token punctuation">][</span>i<span class="token punctuation">]);
|
||
});
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">zip</span><span class="token punctuation">([</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">], [</span><span class="token boolean">true</span><span class="token punctuation">,</span> <span class="token boolean">false</span><span class="token punctuation">]);</span> <span class="token comment">// [['a', 1, true], ['b', 2, false]]</span>
|
||
<span class="token function">zip</span><span class="token punctuation">([</span><span class="token string">'a'</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">], [</span><span class="token boolean">true</span><span class="token punctuation">,</span> <span class="token boolean">false</span><span class="token punctuation">]);</span> <span class="token comment">// [['a', 1, true], [undefined, 2, false]]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="zipobject" class="section double-padded">zipObject</h3><div class="section double-padded"><p>Given an array of valid property identifiers and an array of values, return an object associating the properties to the values.</p><p>Since an object can have undefined values but not undefined property pointers, the array of properties is used to decide the structure of the resulting object using <code>Array.reduce()</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">zipObject</span> <span class="token operator">=</span> <span class="token punctuation">(</span>props<span class="token punctuation">,</span> values<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
props<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>obj<span class="token punctuation">,</span> prop<span class="token punctuation">,</span> index<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">((</span>obj<span class="token punctuation">[</span>prop<span class="token punctuation">]</span> <span class="token operator">=</span> values<span class="token punctuation">[</span>index<span class="token punctuation">]),</span> obj<span class="token punctuation">), {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">zipObject</span><span class="token punctuation">([</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token string">'c'</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]);</span> <span class="token comment">// {a: 1, b: 2, c: undefined}</span>
|
||
<span class="token function">zipObject</span><span class="token punctuation">([</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">], [</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// {a: 1, b: 2}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Browser</h2><div class="card fluid"><h3 id="arraytohtmllist" class="section double-padded">arrayToHtmlList</h3><div class="section double-padded"><p>Converts the given array elements into <code><li></code> tags and appends them to the list of the given id.</p><p>Use <code>Array.map()</code> and <code>document.querySelector()</code> to create a list of html tags.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">arrayToHtmlList</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> listID<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>item <span class="token operator">=></span> <span class="token punctuation">(</span>document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'#'</span> <span class="token operator">+</span> listID<span class="token punctuation">).</span>innerHTML <span class="token operator">+=</span> <span class="token template-string"><span class="token string">`<li></span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>item<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string"></li>`</span></span><span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">arrayToHtmlList</span><span class="token punctuation">([</span><span class="token string">'item 1'</span><span class="token punctuation">,</span> <span class="token string">'item 2'</span><span class="token punctuation">],</span> <span class="token string">'myListID'</span><span class="token punctuation">);</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="bottomvisible" class="section double-padded">bottomVisible</h3><div class="section double-padded"><p>Returns <code>true</code> if the bottom of the page is visible, <code>false</code> otherwise.</p><p>Use <code>scrollY</code>, <code>scrollHeight</code> and <code>clientHeight</code> to determine if the bottom of the page is visible.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">bottomVisible</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span>
|
||
document<span class="token punctuation">.</span>documentElement<span class="token punctuation">.</span>clientHeight <span class="token operator">+</span> window<span class="token punctuation">.</span>scrollY <span class="token operator">>=</span>
|
||
<span class="token punctuation">(</span>document<span class="token punctuation">.</span>documentElement<span class="token punctuation">.</span>scrollHeight <span class="token operator">||</span> document<span class="token punctuation">.</span>documentElement<span class="token punctuation">.</span>clientHeight<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">bottomVisible</span><span class="token punctuation">();</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="copytoclipboard" class="section double-padded">copyToClipboard<mark class="tag">advanced</mark></h3><div class="section double-padded"><p>Copy a string to the clipboard. Only works as a result of user action (i.e. inside a <code>click</code> event listener).</p><p>Create a new <code><textarea></code> element, fill it with the supplied data and add it to the HTML document. Use <code>Selection.getRangeAt()</code>to store the selected range (if any). Use <code>document.execCommand('copy')</code> to copy to the clipboard. Remove the <code><textarea></code> element from the HTML document. Finally, use <code>Selection().addRange()</code> to recover the original selected range (if any).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">copyToClipboard</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> el <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">createElement</span><span class="token punctuation">(</span><span class="token string">'textarea'</span><span class="token punctuation">);</span>
|
||
el<span class="token punctuation">.</span>value <span class="token operator">=</span> str<span class="token punctuation">;</span>
|
||
el<span class="token punctuation">.</span><span class="token function">setAttribute</span><span class="token punctuation">(</span><span class="token string">'readonly'</span><span class="token punctuation">,</span> <span class="token string">''</span><span class="token punctuation">);</span>
|
||
el<span class="token punctuation">.</span>style<span class="token punctuation">.</span>position <span class="token operator">=</span> <span class="token string">'absolute'</span><span class="token punctuation">;</span>
|
||
el<span class="token punctuation">.</span>style<span class="token punctuation">.</span>left <span class="token operator">=</span> <span class="token string">'-9999px'</span><span class="token punctuation">;</span>
|
||
document<span class="token punctuation">.</span>body<span class="token punctuation">.</span><span class="token function">appendChild</span><span class="token punctuation">(</span>el<span class="token punctuation">);</span>
|
||
<span class="token keyword">const</span> selected <span class="token operator">=</span>
|
||
document<span class="token punctuation">.</span><span class="token function">getSelection</span><span class="token punctuation">().</span>rangeCount <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">?</span> document<span class="token punctuation">.</span><span class="token function">getSelection</span><span class="token punctuation">().</span><span class="token function">getRangeAt</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">) :</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
|
||
el<span class="token punctuation">.</span><span class="token function">select</span><span class="token punctuation">();</span>
|
||
document<span class="token punctuation">.</span><span class="token function">execCommand</span><span class="token punctuation">(</span><span class="token string">'copy'</span><span class="token punctuation">);</span>
|
||
document<span class="token punctuation">.</span>body<span class="token punctuation">.</span><span class="token function">removeChild</span><span class="token punctuation">(</span>el<span class="token punctuation">);</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>selected<span class="token punctuation">) {</span>
|
||
document<span class="token punctuation">.</span><span class="token function">getSelection</span><span class="token punctuation">().</span><span class="token function">removeAllRanges</span><span class="token punctuation">();</span>
|
||
document<span class="token punctuation">.</span><span class="token function">getSelection</span><span class="token punctuation">().</span><span class="token function">addRange</span><span class="token punctuation">(</span>selected<span class="token punctuation">);
|
||
}
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">copyToClipboard</span><span class="token punctuation">(</span><span class="token string">'Lorem ipsum'</span><span class="token punctuation">);</span> <span class="token comment">// 'Lorem ipsum' copied to clipboard.</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="createelement" class="section double-padded">createElement</h3><div class="section double-padded"><p>Creates an element from a string (without appending it to the document). If the given string contains multiple elements, only the first one will be returned.</p><p>Use <code>document.createElement()</code> to create a new element. Set its <code>innerHTML</code> to the string supplied as the argument. Use <code>ParentNode.firstElementChild</code> to return the element version of the string.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">createElement</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> el <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">createElement</span><span class="token punctuation">(</span><span class="token string">'div'</span><span class="token punctuation">);</span>
|
||
el<span class="token punctuation">.</span>innerHTML <span class="token operator">=</span> str<span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> el<span class="token punctuation">.</span>firstElementChild<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> el <span class="token operator">=</span> <span class="token function">createElement</span><span class="token punctuation">(</span>
|
||
<span class="token template-string"><span class="token string">`<div class="container">
|
||
<p>Hello!</p>
|
||
</div>`</span></span>
|
||
<span class="token punctuation">);</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>el<span class="token punctuation">.</span>className<span class="token punctuation">);</span> <span class="token comment">// 'container'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="createeventhub" class="section double-padded">createEventHub<mark class="tag">advanced</mark></h3><div class="section double-padded"><p>Creates a pub/sub (<a href="https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern">publish–subscribe</a>) event hub with <code>emit</code>, <code>on</code>, and <code>off</code> methods.</p><p>Use <code>Object.create(null)</code> to create an empty <code>hub</code> object that does not inherit properties from <code>Object.prototype</code>. For <code>emit</code>, resolve the array of handlers based on the <code>event</code> argument and then run each one with <code>Array.forEach()</code> by passing in the data as an argument. For <code>on</code>, create an array for the event if it does not yet exist, then use <code>Array.push()</code> to add the handler to the array. For <code>off</code>, use <code>Array.findIndex()</code> to find the index of the handler in the event array and remove it using <code>Array.splice()</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">createEventHub</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">({</span>
|
||
hub<span class="token punctuation">:</span> Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">),</span>
|
||
<span class="token function">emit</span><span class="token punctuation">(</span>event<span class="token punctuation">,</span> data<span class="token punctuation">) {
|
||
(</span><span class="token keyword">this</span><span class="token punctuation">.</span>hub<span class="token punctuation">[</span>event<span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token punctuation">[]).</span><span class="token function">forEach</span><span class="token punctuation">(</span>handler <span class="token operator">=></span> <span class="token function">handler</span><span class="token punctuation">(</span>data<span class="token punctuation">));
|
||
},</span>
|
||
<span class="token function">on</span><span class="token punctuation">(</span>event<span class="token punctuation">,</span> handler<span class="token punctuation">) {</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token keyword">this</span><span class="token punctuation">.</span>hub<span class="token punctuation">[</span>event<span class="token punctuation">])</span> <span class="token keyword">this</span><span class="token punctuation">.</span>hub<span class="token punctuation">[</span>event<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[];</span>
|
||
<span class="token keyword">this</span><span class="token punctuation">.</span>hub<span class="token punctuation">[</span>event<span class="token punctuation">].</span><span class="token function">push</span><span class="token punctuation">(</span>handler<span class="token punctuation">);
|
||
},</span>
|
||
<span class="token function">off</span><span class="token punctuation">(</span>event<span class="token punctuation">,</span> handler<span class="token punctuation">) {</span>
|
||
<span class="token keyword">const</span> i <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>hub<span class="token punctuation">[</span>event<span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token punctuation">[]).</span><span class="token function">findIndex</span><span class="token punctuation">(</span>h <span class="token operator">=></span> h <span class="token operator">===</span> handler<span class="token punctuation">);</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>i <span class="token operator">> -</span><span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">this</span><span class="token punctuation">.</span>hub<span class="token punctuation">[</span>event<span class="token punctuation">].</span><span class="token function">splice</span><span class="token punctuation">(</span>i<span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">);
|
||
}
|
||
});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">handler</span> <span class="token operator">=</span> data <span class="token operator">=></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>data<span class="token punctuation">);</span>
|
||
<span class="token keyword">const</span> hub <span class="token operator">=</span> <span class="token function">createEventHub</span><span class="token punctuation">();</span>
|
||
<span class="token keyword">let</span> increment <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
|
||
<span class="token comment">// Subscribe: listen for different types of events</span>
|
||
hub<span class="token punctuation">.</span><span class="token function">on</span><span class="token punctuation">(</span><span class="token string">'message'</span><span class="token punctuation">,</span> handler<span class="token punctuation">);</span>
|
||
hub<span class="token punctuation">.</span><span class="token function">on</span><span class="token punctuation">(</span><span class="token string">'message'</span><span class="token punctuation">, ()</span> <span class="token operator">=></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'Message event fired'</span><span class="token punctuation">));</span>
|
||
hub<span class="token punctuation">.</span><span class="token function">on</span><span class="token punctuation">(</span><span class="token string">'increment'</span><span class="token punctuation">, ()</span> <span class="token operator">=></span> increment<span class="token operator">++</span><span class="token punctuation">);</span>
|
||
|
||
<span class="token comment">// Publish: emit events to invoke all handlers subscribed to them, passing the data to them as an argument</span>
|
||
hub<span class="token punctuation">.</span><span class="token function">emit</span><span class="token punctuation">(</span><span class="token string">'message'</span><span class="token punctuation">,</span> <span class="token string">'hello world'</span><span class="token punctuation">);</span> <span class="token comment">// logs 'hello world' and 'Message event fired'</span>
|
||
hub<span class="token punctuation">.</span><span class="token function">emit</span><span class="token punctuation">(</span><span class="token string">'message'</span><span class="token punctuation">, {</span> hello<span class="token punctuation">:</span> <span class="token string">'world'</span> <span class="token punctuation">});</span> <span class="token comment">// logs the object and 'Message event fired'</span>
|
||
hub<span class="token punctuation">.</span><span class="token function">emit</span><span class="token punctuation">(</span><span class="token string">'increment'</span><span class="token punctuation">);</span> <span class="token comment">// `increment` variable is now 1</span>
|
||
|
||
<span class="token comment">// Unsubscribe: stop a specific handler from listening to the 'message' event</span>
|
||
hub<span class="token punctuation">.</span><span class="token function">off</span><span class="token punctuation">(</span><span class="token string">'message'</span><span class="token punctuation">,</span> handler<span class="token punctuation">);</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="currenturl" class="section double-padded">currentURL</h3><div class="section double-padded"><p>Returns the current URL.</p><p>Use <code>window.location.href</code> to get current URL.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">currentURL</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> window<span class="token punctuation">.</span>location<span class="token punctuation">.</span>href<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">currentURL</span><span class="token punctuation">();</span> <span class="token comment">// 'https://google.com'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="detectdevicetype" class="section double-padded">detectDeviceType</h3><div class="section double-padded"><p>Detects wether the website is being opened in a mobile device or a desktop/laptop.</p><p>Use a regular expression to test the <code>navigator.userAgent</code> property to figure out if the device is a mobile device or a desktop/laptop.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">detectDeviceType</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span>
|
||
<span class="token regex">/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i</span><span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>navigator<span class="token punctuation">.</span>userAgent<span class="token punctuation">)</span>
|
||
<span class="token operator">?</span> <span class="token string">'Mobile'</span>
|
||
<span class="token punctuation">:</span> <span class="token string">'Desktop'</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">detectDeviceType</span><span class="token punctuation">();</span> <span class="token comment">// "Mobile" or "Desktop"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="elementisvisibleinviewport" class="section double-padded">elementIsVisibleInViewport</h3><div class="section double-padded"><p>Returns <code>true</code> if the element specified is visible in the viewport, <code>false</code> otherwise.</p><p>Use <code>Element.getBoundingClientRect()</code> and the <code>window.inner(Width|Height)</code> values to determine if a given element is visible in the viewport. Omit the second argument to determine if the element is entirely visible, or specify <code>true</code> to determine if it is partially visible.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">elementIsVisibleInViewport</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el<span class="token punctuation">,</span> partiallyVisible <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> <span class="token punctuation">{</span> top<span class="token punctuation">,</span> left<span class="token punctuation">,</span> bottom<span class="token punctuation">,</span> right <span class="token punctuation">}</span> <span class="token operator">=</span> el<span class="token punctuation">.</span><span class="token function">getBoundingClientRect</span><span class="token punctuation">();</span>
|
||
<span class="token keyword">const</span> <span class="token punctuation">{</span> innerHeight<span class="token punctuation">,</span> innerWidth <span class="token punctuation">}</span> <span class="token operator">=</span> window<span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> partiallyVisible
|
||
<span class="token operator">?</span> <span class="token punctuation">((</span>top <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">&&</span> top <span class="token operator"><</span> innerHeight<span class="token punctuation">)</span> <span class="token operator">||</span> <span class="token punctuation">(</span>bottom <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">&&</span> bottom <span class="token operator"><</span> innerHeight<span class="token punctuation">))</span> <span class="token operator">&&</span>
|
||
<span class="token punctuation">((</span>left <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">&&</span> left <span class="token operator"><</span> innerWidth<span class="token punctuation">)</span> <span class="token operator">||</span> <span class="token punctuation">(</span>right <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">&&</span> right <span class="token operator"><</span> innerWidth<span class="token punctuation">))
|
||
:</span> top <span class="token operator">>=</span> <span class="token number">0</span> <span class="token operator">&&</span> left <span class="token operator">>=</span> <span class="token number">0</span> <span class="token operator">&&</span> bottom <span class="token operator"><=</span> innerHeight <span class="token operator">&&</span> right <span class="token operator"><=</span> innerWidth<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token comment">// e.g. 100x100 viewport and a 10x10px element at position {top: -1, left: 0, bottom: 9, right: 10}</span>
|
||
<span class="token function">elementIsVisibleInViewport</span><span class="token punctuation">(</span>el<span class="token punctuation">);</span> <span class="token comment">// false - (not fully visible)</span>
|
||
<span class="token function">elementIsVisibleInViewport</span><span class="token punctuation">(</span>el<span class="token punctuation">,</span> <span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// true - (partially visible)</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="getscrollposition" class="section double-padded">getScrollPosition</h3><div class="section double-padded"><p>Returns the scroll position of the current page.</p><p>Use <code>pageXOffset</code> and <code>pageYOffset</code> if they are defined, otherwise <code>scrollLeft</code> and <code>scrollTop</code>. You can omit <code>el</code> to use a default value of <code>window</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">getScrollPosition</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el <span class="token operator">=</span> window<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">({</span>
|
||
x<span class="token punctuation">:</span> el<span class="token punctuation">.</span>pageXOffset <span class="token operator">!==</span> undefined <span class="token operator">?</span> el<span class="token punctuation">.</span>pageXOffset <span class="token punctuation">:</span> el<span class="token punctuation">.</span>scrollLeft<span class="token punctuation">,</span>
|
||
y<span class="token punctuation">:</span> el<span class="token punctuation">.</span>pageYOffset <span class="token operator">!==</span> undefined <span class="token operator">?</span> el<span class="token punctuation">.</span>pageYOffset <span class="token punctuation">:</span> el<span class="token punctuation">.</span>scrollTop
|
||
<span class="token punctuation">});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">getScrollPosition</span><span class="token punctuation">();</span> <span class="token comment">// {x: 0, y: 200}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="getstyle" class="section double-padded">getStyle</h3><div class="section double-padded"><p>Returns the value of a CSS rule for the specified element.</p><p>Use <code>Window.getComputedStyle()</code> to get the value of the CSS rule for the specified element.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">getStyle</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el<span class="token punctuation">,</span> ruleName<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">getComputedStyle</span><span class="token punctuation">(</span>el<span class="token punctuation">)[</span>ruleName<span class="token punctuation">];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">getStyle</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'p'</span><span class="token punctuation">),</span> <span class="token string">'font-size'</span><span class="token punctuation">);</span> <span class="token comment">// '16px'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="hasclass" class="section double-padded">hasClass</h3><div class="section double-padded"><p>Returns <code>true</code> if the element has the specified class, <code>false</code> otherwise.</p><p>Use <code>element.classList.contains()</code> to check if the element has the specified class.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">hasClass</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el<span class="token punctuation">,</span> className<span class="token punctuation">)</span> <span class="token operator">=></span> el<span class="token punctuation">.</span>classList<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span>className<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">hasClass</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'p.special'</span><span class="token punctuation">),</span> <span class="token string">'special'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="hide" class="section double-padded">hide</h3><div class="section double-padded"><p>Hides all the elements specified.</p><p>Use the spread operator (<code>...</code>) and <code>Array.forEach()</code> to apply <code>display: none</code> to each element specified.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">hide</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>el<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>el<span class="token punctuation">].</span><span class="token function">forEach</span><span class="token punctuation">(</span>e <span class="token operator">=></span> <span class="token punctuation">(</span>e<span class="token punctuation">.</span>style<span class="token punctuation">.</span>display <span class="token operator">=</span> <span class="token string">'none'</span><span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">hide</span><span class="token punctuation">(</span><span class="token operator">...</span>document<span class="token punctuation">.</span><span class="token function">querySelectorAll</span><span class="token punctuation">(</span><span class="token string">'img'</span><span class="token punctuation">));</span> <span class="token comment">// Hides all <img> elements on the page</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="httpsredirect" class="section double-padded">httpsRedirect</h3><div class="section double-padded"><p>Redirects the page to HTTPS if its currently in HTTP. Also, pressing the back button doesn't take it back to the HTTP page as its replaced in the history.</p><p>Use <code>location.protocol</code> to get the protocol currently being used. If it's not HTTPS, use <code>location.replace()</code> to replace the existing page with the HTTPS version of the page. Use <code>location.href</code> to get the full address, split it with <code>String.split()</code> and remove the protocol part of the URL.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">httpsRedirect</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>location<span class="token punctuation">.</span>protocol <span class="token operator">!==</span> <span class="token string">'https:'</span><span class="token punctuation">)</span> location<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token string">'https://'</span> <span class="token operator">+</span> location<span class="token punctuation">.</span>href<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">'//'</span><span class="token punctuation">)[</span><span class="token number">1</span><span class="token punctuation">]);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">httpsRedirect</span><span class="token punctuation">();</span> <span class="token comment">// If you are on http://mydomain.com, you are redirected to https://mydomain.com</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="off" class="section double-padded">off</h3><div class="section double-padded"><p>Removes an event listener from an element.</p><p>Use <code>EventTarget.removeEventListener()</code> to remove an event listener from an element. Omit the fourth argument <code>opts</code> to use <code>false</code> or specify it based on the options used when the event listener was added.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">off</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el<span class="token punctuation">,</span> evt<span class="token punctuation">,</span> fn<span class="token punctuation">,</span> opts <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">)</span> <span class="token operator">=></span> el<span class="token punctuation">.</span><span class="token function">removeEventListener</span><span class="token punctuation">(</span>evt<span class="token punctuation">,</span> fn<span class="token punctuation">,</span> opts<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">fn</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'!'</span><span class="token punctuation">);</span>
|
||
document<span class="token punctuation">.</span>body<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> fn<span class="token punctuation">);</span>
|
||
<span class="token function">off</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span>body<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">,</span> fn<span class="token punctuation">);</span> <span class="token comment">// no longer logs '!' upon clicking on the page</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="on" class="section double-padded">on</h3><div class="section double-padded"><p>Adds an event listener to an element with the ability to use event delegation.</p><p>Use <code>EventTarget.addEventListener()</code> to add an event listener to an element. If there is a <code>target</code> property supplied to the options object, ensure the event target matches the target specified and then invoke the callback by supplying the correct <code>this</code> context. Returns a reference to the custom delegator function, in order to be possible to use with <a href="#off"><code>off</code></a>. Omit <code>opts</code> to default to non-delegation behavior and event bubbling.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">on</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el<span class="token punctuation">,</span> evt<span class="token punctuation">,</span> fn<span class="token punctuation">,</span> opts <span class="token operator">=</span> <span class="token punctuation">{})</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">delegatorFn</span> <span class="token operator">=</span> e <span class="token operator">=></span> e<span class="token punctuation">.</span>target<span class="token punctuation">.</span><span class="token function">matches</span><span class="token punctuation">(</span>opts<span class="token punctuation">.</span>target<span class="token punctuation">)</span> <span class="token operator">&&</span> fn<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>e<span class="token punctuation">.</span>target<span class="token punctuation">,</span> e<span class="token punctuation">);</span>
|
||
el<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span>evt<span class="token punctuation">,</span> opts<span class="token punctuation">.</span>target <span class="token operator">?</span> delegatorFn <span class="token punctuation">:</span> fn<span class="token punctuation">,</span> opts<span class="token punctuation">.</span>options <span class="token operator">||</span> <span class="token boolean">false</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>opts<span class="token punctuation">.</span>target<span class="token punctuation">)</span> <span class="token keyword">return</span> delegatorFn<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">fn</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'!'</span><span class="token punctuation">);</span>
|
||
<span class="token function">on</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span>body<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">,</span> fn<span class="token punctuation">);</span> <span class="token comment">// logs '!' upon clicking the body</span>
|
||
<span class="token function">on</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span>body<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">,</span> fn<span class="token punctuation">, {</span> target<span class="token punctuation">:</span> <span class="token string">'p'</span> <span class="token punctuation">});</span> <span class="token comment">// logs '!' upon clicking a `p` element child of the body</span>
|
||
<span class="token function">on</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span>body<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">,</span> fn<span class="token punctuation">, {</span> options<span class="token punctuation">:</span> <span class="token boolean">true</span> <span class="token punctuation">});</span> <span class="token comment">// use capturing instead of bubbling</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="onuserinputchange" class="section double-padded">onUserInputChange<mark class="tag">advanced</mark></h3><div class="section double-padded"><p>Run the callback whenever the user input type changes (<code>mouse</code> or <code>touch</code>). Useful for enabling/disabling code depending on the input device. This process is dynamic and works with hybrid devices (e.g. touchscreen laptops).</p><p>Use two event listeners. Assume <code>mouse</code> input initially and bind a <code>touchstart</code> event listener to the document. On <code>touchstart</code>, add a <code>mousemove</code> event listener to listen for two consecutive <code>mousemove</code> events firing within 20ms, using <code>performance.now()</code>. Run the callback with the input type as an argument in either of these situations.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">onUserInputChange</span> <span class="token operator">=</span> callback <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> type <span class="token operator">=</span> <span class="token string">'mouse'</span><span class="token punctuation">,</span>
|
||
lastTime <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">mousemoveHandler</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> now <span class="token operator">=</span> performance<span class="token punctuation">.</span><span class="token function">now</span><span class="token punctuation">();</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>now <span class="token operator">-</span> lastTime <span class="token operator"><</span> <span class="token number">20</span><span class="token punctuation">)
|
||
(</span>type <span class="token operator">=</span> <span class="token string">'mouse'</span><span class="token punctuation">),</span> <span class="token function">callback</span><span class="token punctuation">(</span>type<span class="token punctuation">),</span> document<span class="token punctuation">.</span><span class="token function">removeEventListener</span><span class="token punctuation">(</span><span class="token string">'mousemove'</span><span class="token punctuation">,</span> mousemoveHandler<span class="token punctuation">);</span>
|
||
lastTime <span class="token operator">=</span> now<span class="token punctuation">;
|
||
};</span>
|
||
document<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'touchstart'</span><span class="token punctuation">, ()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>type <span class="token operator">===</span> <span class="token string">'touch'</span><span class="token punctuation">)</span> <span class="token keyword">return</span><span class="token punctuation">;
|
||
(</span>type <span class="token operator">=</span> <span class="token string">'touch'</span><span class="token punctuation">),</span> <span class="token function">callback</span><span class="token punctuation">(</span>type<span class="token punctuation">),</span> document<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'mousemove'</span><span class="token punctuation">,</span> mousemoveHandler<span class="token punctuation">);
|
||
});
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">onUserInputChange</span><span class="token punctuation">(</span>type <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'The user is now using'</span><span class="token punctuation">,</span> type<span class="token punctuation">,</span> <span class="token string">'as an input method.'</span><span class="token punctuation">);
|
||
});</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="redirect" class="section double-padded">redirect</h3><div class="section double-padded"><p>Redirects to a specified URL.</p><p>Use <code>window.location.href</code> or <code>window.location.replace()</code> to redirect to <code>url</code>. Pass a second argument to simulate a link click (<code>true</code> - default) or an HTTP redirect (<code>false</code>).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">redirect</span> <span class="token operator">=</span> <span class="token punctuation">(</span>url<span class="token punctuation">,</span> asLink <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
asLink <span class="token operator">?</span> <span class="token punctuation">(</span>window<span class="token punctuation">.</span>location<span class="token punctuation">.</span>href <span class="token operator">=</span> url<span class="token punctuation">) :</span> window<span class="token punctuation">.</span>location<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span>url<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">redirect</span><span class="token punctuation">(</span><span class="token string">'https://google.com'</span><span class="token punctuation">);</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="runasync" class="section double-padded">runAsync<mark class="tag">advanced</mark></h3><div class="section double-padded"><p>Runs a function in a separate thread by using a <a href="https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Using_web_workers">Web Worker</a>, allowing long running functions to not block the UI.</p><p>Create a new <code>Worker</code> using a <code>Blob</code> object URL, the contents of which should be the stringified version of the supplied function. Immediately post the return value of calling the function back. Return a promise, listening for <code>onmessage</code> and <code>onerror</code> events and resolving the data posted back from the worker, or throwing an error.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">runAsync</span> <span class="token operator">=</span> fn <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> blob <span class="token operator">=</span> <span class="token template-string"><span class="token string">`var fn = </span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>fn<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">()</span><span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">; postMessage(fn());`</span></span><span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> worker <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Worker</span><span class="token punctuation">(</span>
|
||
URL<span class="token punctuation">.</span><span class="token function">createObjectURL</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Blob</span><span class="token punctuation">([</span>blob<span class="token punctuation">]), {</span>
|
||
type<span class="token punctuation">:</span> <span class="token string">'application/javascript; charset=utf-8'</span>
|
||
<span class="token punctuation">})
|
||
);</span>
|
||
<span class="token keyword">return new</span> <span class="token class-name">Promise</span><span class="token punctuation">((</span>res<span class="token punctuation">,</span> rej<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
worker<span class="token punctuation">.</span><span class="token function-variable function">onmessage</span> <span class="token operator">=</span> <span class="token punctuation">({</span> data <span class="token punctuation">})</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token function">res</span><span class="token punctuation">(</span>data<span class="token punctuation">),</span> worker<span class="token punctuation">.</span><span class="token function">terminate</span><span class="token punctuation">();
|
||
};</span>
|
||
worker<span class="token punctuation">.</span><span class="token function-variable function">onerror</span> <span class="token operator">=</span> err <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token function">rej</span><span class="token punctuation">(</span>err<span class="token punctuation">),</span> worker<span class="token punctuation">.</span><span class="token function">terminate</span><span class="token punctuation">();
|
||
};
|
||
});
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">longRunningFunction</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> result <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> <span class="token number">1000</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">) {</span>
|
||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> j <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> j <span class="token operator"><</span> <span class="token number">700</span><span class="token punctuation">;</span> j<span class="token operator">++</span><span class="token punctuation">) {</span>
|
||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> k <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> k <span class="token operator"><</span> <span class="token number">300</span><span class="token punctuation">;</span> k<span class="token operator">++</span><span class="token punctuation">) {</span>
|
||
result <span class="token operator">=</span> result <span class="token operator">+</span> i <span class="token operator">+</span> j <span class="token operator">+</span> k<span class="token punctuation">;
|
||
}
|
||
}
|
||
}</span>
|
||
<span class="token keyword">return</span> result<span class="token punctuation">;
|
||
};</span>
|
||
<span class="token comment">/*
|
||
NOTE: Since the function is running in a different context, closures are not supported.
|
||
The function supplied to `runAsync` gets stringified, so everything becomes literal.
|
||
All variables and functions must be defined inside.
|
||
*/</span>
|
||
<span class="token function">runAsync</span><span class="token punctuation">(</span>longRunningFunction<span class="token punctuation">).</span><span class="token function">then</span><span class="token punctuation">(</span>console<span class="token punctuation">.</span>log<span class="token punctuation">);</span> <span class="token comment">// 209685000000</span>
|
||
<span class="token function">runAsync</span><span class="token punctuation">(()</span> <span class="token operator">=></span> <span class="token number">10</span> <span class="token operator">**</span> <span class="token number">3</span><span class="token punctuation">).</span><span class="token function">then</span><span class="token punctuation">(</span>console<span class="token punctuation">.</span>log<span class="token punctuation">);</span> <span class="token comment">// 1000</span>
|
||
<span class="token keyword">let</span> outsideVariable <span class="token operator">=</span> <span class="token number">50</span><span class="token punctuation">;</span>
|
||
<span class="token function">runAsync</span><span class="token punctuation">(()</span> <span class="token operator">=></span> <span class="token keyword">typeof</span> outsideVariable<span class="token punctuation">).</span><span class="token function">then</span><span class="token punctuation">(</span>console<span class="token punctuation">.</span>log<span class="token punctuation">);</span> <span class="token comment">// 'undefined'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="scrolltotop" class="section double-padded">scrollToTop</h3><div class="section double-padded"><p>Smooth-scrolls to the top of the page.</p><p>Get distance from top using <code>document.documentElement.scrollTop</code> or <code>document.body.scrollTop</code>. Scroll by a fraction of the distance from the top. Use <code>window.requestAnimationFrame()</code> to animate the scrolling.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">scrollToTop</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> c <span class="token operator">=</span> document<span class="token punctuation">.</span>documentElement<span class="token punctuation">.</span>scrollTop <span class="token operator">||</span> document<span class="token punctuation">.</span>body<span class="token punctuation">.</span>scrollTop<span class="token punctuation">;</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>c <span class="token operator">></span> <span class="token number">0</span><span class="token punctuation">) {</span>
|
||
window<span class="token punctuation">.</span><span class="token function">requestAnimationFrame</span><span class="token punctuation">(</span>scrollToTop<span class="token punctuation">);</span>
|
||
window<span class="token punctuation">.</span><span class="token function">scrollTo</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> c <span class="token operator">-</span> c <span class="token operator">/</span> <span class="token number">8</span><span class="token punctuation">);
|
||
}
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">scrollToTop</span><span class="token punctuation">();</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="setstyle" class="section double-padded">setStyle</h3><div class="section double-padded"><p>Sets the value of a CSS rule for the specified element.</p><p>Use <code>element.style</code> to set the value of the CSS rule for the specified element to <code>val</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">setStyle</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el<span class="token punctuation">,</span> ruleName<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>el<span class="token punctuation">.</span>style<span class="token punctuation">[</span>ruleName<span class="token punctuation">]</span> <span class="token operator">=</span> val<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">setStyle</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'p'</span><span class="token punctuation">),</span> <span class="token string">'font-size'</span><span class="token punctuation">,</span> <span class="token string">'20px'</span><span class="token punctuation">);</span> <span class="token comment">// The first <p> element on the page will have a font-size of 20px</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="show" class="section double-padded">show</h3><div class="section double-padded"><p>Shows all the elements specified.</p><p>Use the spread operator (<code>...</code>) and <code>Array.forEach()</code> to clear the <code>display</code> property for each element specified.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">show</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>el<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>el<span class="token punctuation">].</span><span class="token function">forEach</span><span class="token punctuation">(</span>e <span class="token operator">=></span> <span class="token punctuation">(</span>e<span class="token punctuation">.</span>style<span class="token punctuation">.</span>display <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">show</span><span class="token punctuation">(</span><span class="token operator">...</span>document<span class="token punctuation">.</span><span class="token function">querySelectorAll</span><span class="token punctuation">(</span><span class="token string">'img'</span><span class="token punctuation">));</span> <span class="token comment">// Shows all <img> elements on the page</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="toggleclass" class="section double-padded">toggleClass</h3><div class="section double-padded"><p>Toggle a class for an element.</p><p>Use <code>element.classList.toggle()</code> to toggle the specified class for the element.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">toggleClass</span> <span class="token operator">=</span> <span class="token punctuation">(</span>el<span class="token punctuation">,</span> className<span class="token punctuation">)</span> <span class="token operator">=></span> el<span class="token punctuation">.</span>classList<span class="token punctuation">.</span><span class="token function">toggle</span><span class="token punctuation">(</span>className<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">toggleClass</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'p.special'</span><span class="token punctuation">),</span> <span class="token string">'special'</span><span class="token punctuation">);</span> <span class="token comment">// The paragraph will not have the 'special' class anymore</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="uuidgeneratorbrowser" class="section double-padded">UUIDGeneratorBrowser</h3><div class="section double-padded"><p>Generates a UUID in a browser.</p><p>Use <code>crypto</code> API to generate a UUID, compliant with <a href="https://www.ietf.org/rfc/rfc4122.txt">RFC4122</a> version 4.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">UUIDGeneratorBrowser</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">([</span><span class="token number">1e7</span><span class="token punctuation">]</span> <span class="token operator">+ -</span><span class="token number">1e3</span> <span class="token operator">+ -</span><span class="token number">4e3</span> <span class="token operator">+ -</span><span class="token number">8e3</span> <span class="token operator">+ -</span><span class="token number">1e11</span><span class="token punctuation">).</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/[018]/g</span><span class="token punctuation">,</span> c <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span>c <span class="token operator">^</span> <span class="token punctuation">(</span>crypto<span class="token punctuation">.</span><span class="token function">getRandomValues</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Uint8Array</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">))[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">&</span> <span class="token punctuation">(</span><span class="token number">15</span> <span class="token operator">>></span> <span class="token punctuation">(</span>c <span class="token operator">/</span> <span class="token number">4</span><span class="token punctuation">)))).</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token number">16</span><span class="token punctuation">)
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">UUIDGeneratorBrowser</span><span class="token punctuation">();</span> <span class="token comment">// '7982fcfe-5721-4632-bede-6000885be57d'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Date</h2><div class="card fluid"><h3 id="formatduration" class="section double-padded">formatDuration</h3><div class="section double-padded"><p>Returns the human readable format of the given number of milliseconds.</p><p>Divide <code>ms</code> with the appropriate values to obtain the appropriate values for <code>day</code>, <code>hour</code>, <code>minute</code>, <code>second</code> and <code>millisecond</code>. Use <code>Object.entries()</code> with <code>Array.filter()</code> to keep only non-zero values. Use <code>Array.map()</code> to create the string for each value, pluralizing appropriately. Use <code>String.join(', ')</code> to combine the values into a string.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">formatDuration</span> <span class="token operator">=</span> ms <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>ms <span class="token operator"><</span> <span class="token number">0</span><span class="token punctuation">)</span> ms <span class="token operator">= -</span>ms<span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> time <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
day<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>ms <span class="token operator">/</span> <span class="token number">86400000</span><span class="token punctuation">),</span>
|
||
hour<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>ms <span class="token operator">/</span> <span class="token number">3600000</span><span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">24</span><span class="token punctuation">,</span>
|
||
minute<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>ms <span class="token operator">/</span> <span class="token number">60000</span><span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">60</span><span class="token punctuation">,</span>
|
||
second<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>ms <span class="token operator">/</span> <span class="token number">1000</span><span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">60</span><span class="token punctuation">,</span>
|
||
millisecond<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>ms<span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">1000</span>
|
||
<span class="token punctuation">};</span>
|
||
<span class="token keyword">return</span> Object<span class="token punctuation">.</span><span class="token function">entries</span><span class="token punctuation">(</span>time<span class="token punctuation">)
|
||
.</span><span class="token function">filter</span><span class="token punctuation">(</span>val <span class="token operator">=></span> val<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">!==</span> <span class="token number">0</span><span class="token punctuation">)
|
||
.</span><span class="token function">map</span><span class="token punctuation">(</span>val <span class="token operator">=></span> val<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">+</span> <span class="token string">' '</span> <span class="token operator">+</span> <span class="token punctuation">(</span>val<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">!==</span> <span class="token number">1</span> <span class="token operator">?</span> val<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">+</span> <span class="token string">'s'</span> <span class="token punctuation">:</span> val<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]))
|
||
.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">', '</span><span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">formatDuration</span><span class="token punctuation">(</span><span class="token number">1001</span><span class="token punctuation">);</span> <span class="token comment">// '1 second, 1 millisecond'</span>
|
||
<span class="token function">formatDuration</span><span class="token punctuation">(</span><span class="token number">34325055574</span><span class="token punctuation">);</span> <span class="token comment">// '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="getdaysdiffbetweendates" class="section double-padded">getDaysDiffBetweenDates</h3><div class="section double-padded"><p>Returns the difference (in days) between two dates.</p><p>Calculate the difference (in days) between two <code>Date</code> objects.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">getDaysDiffBetweenDates</span> <span class="token operator">=</span> <span class="token punctuation">(</span>dateInitial<span class="token punctuation">,</span> dateFinal<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span>dateFinal <span class="token operator">-</span> dateInitial<span class="token punctuation">)</span> <span class="token operator">/</span> <span class="token punctuation">(</span><span class="token number">1000</span> <span class="token operator">*</span> <span class="token number">3600</span> <span class="token operator">*</span> <span class="token number">24</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">getDaysDiffBetweenDates</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">(</span><span class="token string">'2017-12-13'</span><span class="token punctuation">),</span> <span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">(</span><span class="token string">'2017-12-22'</span><span class="token punctuation">));</span> <span class="token comment">// 9</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="tomorrow" class="section double-padded">tomorrow</h3><div class="section double-padded"><p>Results in a string representation of tomorrow's date. Use <code>new Date()</code> to get today's date, adding <code>86400000</code> of seconds to it(24 hours), using <code>Date.toISOString()</code> to convert Date object to string.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">tomorrow</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">().</span><span class="token function">getTime</span><span class="token punctuation">()</span> <span class="token operator">+</span> <span class="token number">86400000</span><span class="token punctuation">).</span><span class="token function">toISOString</span><span class="token punctuation">().</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">'T'</span><span class="token punctuation">)[</span><span class="token number">0</span><span class="token punctuation">];</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">tomorrow</span><span class="token punctuation">();</span> <span class="token comment">// 2017-12-27 (if current date is 2017-12-26)</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Function</h2><div class="card fluid"><h3 id="chainasync" class="section double-padded">chainAsync</h3><div class="section double-padded"><p>Chains asynchronous functions.</p><p>Loop through an array of functions containing asynchronous events, calling <code>next</code> when each asynchronous event has completed.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">chainAsync</span> <span class="token operator">=</span> fns <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> curr <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">next</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> fns<span class="token punctuation">[</span>curr<span class="token operator">++</span><span class="token punctuation">](</span>next<span class="token punctuation">);</span>
|
||
<span class="token function">next</span><span class="token punctuation">();
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">chainAsync</span><span class="token punctuation">([</span>
|
||
next <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'0 seconds'</span><span class="token punctuation">);</span>
|
||
<span class="token function">setTimeout</span><span class="token punctuation">(</span>next<span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">);
|
||
},</span>
|
||
next <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'1 second'</span><span class="token punctuation">);
|
||
}
|
||
]);</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="compose" class="section double-padded">compose</h3><div class="section double-padded"><p>Performs right-to-left function composition.</p><p>Use <code>Array.reduce()</code> to perform right-to-left function composition. The last (rightmost) function can accept one or more arguments; the remaining functions must be unary.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">compose</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>fns<span class="token punctuation">)</span> <span class="token operator">=></span> fns<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>f<span class="token punctuation">,</span> g<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">f</span><span class="token punctuation">(</span><span class="token function">g</span><span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">add5</span> <span class="token operator">=</span> x <span class="token operator">=></span> x <span class="token operator">+</span> <span class="token number">5</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">multiply</span> <span class="token operator">=</span> <span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">)</span> <span class="token operator">=></span> x <span class="token operator">*</span> y<span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> multiplyAndAdd5 <span class="token operator">=</span> <span class="token function">compose</span><span class="token punctuation">(</span>add5<span class="token punctuation">,</span> multiply<span class="token punctuation">);</span>
|
||
<span class="token function">multiplyAndAdd5</span><span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// 15</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="curry" class="section double-padded">curry</h3><div class="section double-padded"><p>Curries a function.</p><p>Use recursion. If the number of provided arguments (<code>args</code>) is sufficient, call the passed function <code>fn</code>. Otherwise, return a curried function <code>fn</code> that expects the rest of the arguments. If you want to curry a function that accepts a variable number of arguments (a variadic function, e.g. <code>Math.min()</code>), you can optionally pass the number of arguments to the second parameter <code>arity</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">curry</span> <span class="token operator">=</span> <span class="token punctuation">(</span>fn<span class="token punctuation">,</span> arity <span class="token operator">=</span> fn<span class="token punctuation">.</span>length<span class="token punctuation">,</span> <span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arity <span class="token operator"><=</span> args<span class="token punctuation">.</span>length <span class="token operator">?</span> <span class="token function">fn</span><span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">) :</span> curry<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">,</span> fn<span class="token punctuation">,</span> arity<span class="token punctuation">,</span> <span class="token operator">...</span>args<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">curry</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span>pow<span class="token punctuation">)(</span><span class="token number">2</span><span class="token punctuation">)(</span><span class="token number">10</span><span class="token punctuation">);</span> <span class="token comment">// 1024</span>
|
||
<span class="token function">curry</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span>min<span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)(</span><span class="token number">10</span><span class="token punctuation">)(</span><span class="token number">50</span><span class="token punctuation">)(</span><span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// 2</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="defer" class="section double-padded">defer</h3><div class="section double-padded"><p>Defers invoking a function until the current call stack has cleared.</p><p>Use <code>setTimeout()</code> with a timeout of 1ms to add a new event to the browser event queue and allow the rendering engine to complete its work. Use the spread (<code>...</code>) operator to supply the function with an arbitrary number of arguments.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">defer</span> <span class="token operator">=</span> <span class="token punctuation">(</span>fn<span class="token punctuation">,</span> <span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">setTimeout</span><span class="token punctuation">(</span>fn<span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">...</span>args<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token comment">// Example A:</span>
|
||
<span class="token function">defer</span><span class="token punctuation">(</span>console<span class="token punctuation">.</span>log<span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">),</span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'b'</span><span class="token punctuation">);</span> <span class="token comment">// logs 'b' then 'a'</span>
|
||
|
||
<span class="token comment">// Example B:</span>
|
||
document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'#someElement'</span><span class="token punctuation">).</span>innerHTML <span class="token operator">=</span> <span class="token string">'Hello'</span><span class="token punctuation">;</span>
|
||
<span class="token function">longRunningFunction</span><span class="token punctuation">();</span> <span class="token comment">//Browser will not update the HTML until this has finished</span>
|
||
<span class="token function">defer</span><span class="token punctuation">(</span>longRunningFunction<span class="token punctuation">);</span> <span class="token comment">// Browser will update the HTML then run the function</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="functionname" class="section double-padded">functionName</h3><div class="section double-padded"><p>Logs the name of a function.</p><p>Use <code>console.debug()</code> and the <code>name</code> property of the passed method to log the method's name to the <code>debug</code> channel of the console.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">functionName</span> <span class="token operator">=</span> fn <span class="token operator">=></span> <span class="token punctuation">(</span>console<span class="token punctuation">.</span><span class="token function">debug</span><span class="token punctuation">(</span>fn<span class="token punctuation">.</span>name<span class="token punctuation">),</span> fn<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">functionName</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span>max<span class="token punctuation">);</span> <span class="token comment">// max (logged in debug channel of console)</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="memoize" class="section double-padded">memoize</h3><div class="section double-padded"><p>Returns the memoized (cached) function.</p><p>Create an empty cache by instantiating a new <code>Map</code> object. Return a function which takes a single argument to be supplied to the memoized function by first checking if the function's output for that specific input value is already cached, or store and return it if not. The <code>function</code> keyword must be used in order to allow the memoized function to have its <code>this</code> context changed if necessary. Allow access to the <code>cache</code> by setting it as a property on the returned function.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">memoize</span> <span class="token operator">=</span> fn <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> cache <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Map</span><span class="token punctuation">();</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">cached</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span>val<span class="token punctuation">) {</span>
|
||
<span class="token keyword">return</span> cache<span class="token punctuation">.</span><span class="token function">has</span><span class="token punctuation">(</span>val<span class="token punctuation">)</span> <span class="token operator">?</span> cache<span class="token punctuation">.</span><span class="token keyword">get</span><span class="token punctuation">(</span>val<span class="token punctuation">) :</span> cache<span class="token punctuation">.</span><span class="token keyword">set</span><span class="token punctuation">(</span>val<span class="token punctuation">,</span> fn<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> val<span class="token punctuation">))</span> <span class="token operator">&&</span> cache<span class="token punctuation">.</span><span class="token keyword">get</span><span class="token punctuation">(</span>val<span class="token punctuation">);
|
||
};</span>
|
||
cached<span class="token punctuation">.</span>cache <span class="token operator">=</span> cache<span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> cached<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token comment">// See the `anagrams` snippet.</span>
|
||
<span class="token keyword">const</span> anagramsCached <span class="token operator">=</span> <span class="token function">memoize</span><span class="token punctuation">(</span>anagrams<span class="token punctuation">);</span>
|
||
<span class="token function">anagramsCached</span><span class="token punctuation">(</span><span class="token string">'javascript'</span><span class="token punctuation">);</span> <span class="token comment">// takes a long time</span>
|
||
<span class="token function">anagramsCached</span><span class="token punctuation">(</span><span class="token string">'javascript'</span><span class="token punctuation">);</span> <span class="token comment">// returns virtually instantly since it's now cached</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>anagramsCached<span class="token punctuation">.</span>cache<span class="token punctuation">);</span> <span class="token comment">// The cached anagrams map</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="negate" class="section double-padded">negate</h3><div class="section double-padded"><p>Negates a predicate function.</p><p>Take a predicate function and apply the not operator (<code>!</code>) to it with its arguments.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">negate</span> <span class="token operator">=</span> func <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=> !</span><span class="token function">func</span><span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token punctuation">].</span><span class="token function">filter</span><span class="token punctuation">(</span><span class="token function">negate</span><span class="token punctuation">(</span>n <span class="token operator">=></span> n <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">));</span> <span class="token comment">// [ 1, 3, 5 ]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="once" class="section double-padded">once</h3><div class="section double-padded"><p>Ensures a function is called only once.</p><p>Utilizing a closure, use a flag, <code>called</code>, and set it to <code>true</code> once the function is called for the first time, preventing it from being called again. In order to allow the function to have its <code>this</code> context changed (such as in an event listener), the <code>function</code> keyword must be used, and the supplied function must have the context applied. Allow the function to be supplied with an arbitrary number of arguments using the rest/spread (<code>...</code>) operator.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">once</span> <span class="token operator">=</span> fn <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> called <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">return function</span><span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">) {</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>called<span class="token punctuation">)</span> <span class="token keyword">return</span><span class="token punctuation">;</span>
|
||
called <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> fn<span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> args<span class="token punctuation">);
|
||
};
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">startApp</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span>event<span class="token punctuation">) {</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> event<span class="token punctuation">);</span> <span class="token comment">// document.body, MouseEvent</span>
|
||
<span class="token punctuation">};</span>
|
||
document<span class="token punctuation">.</span>body<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token function">once</span><span class="token punctuation">(</span>startApp<span class="token punctuation">));</span> <span class="token comment">// only runs `startApp` once upon click</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="runpromisesinseries" class="section double-padded">runPromisesInSeries</h3><div class="section double-padded"><p>Runs an array of promises in series.</p><p>Use <code>Array.reduce()</code> to create a promise chain, where each promise returns the next promise when resolved.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">runPromisesInSeries</span> <span class="token operator">=</span> ps <span class="token operator">=></span> ps<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>p<span class="token punctuation">,</span> next<span class="token punctuation">)</span> <span class="token operator">=></span> p<span class="token punctuation">.</span><span class="token function">then</span><span class="token punctuation">(</span>next<span class="token punctuation">),</span> Promise<span class="token punctuation">.</span><span class="token function">resolve</span><span class="token punctuation">());</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">delay</span> <span class="token operator">=</span> d <span class="token operator">=></span> <span class="token keyword">new</span> <span class="token class-name">Promise</span><span class="token punctuation">(</span>r <span class="token operator">=></span> <span class="token function">setTimeout</span><span class="token punctuation">(</span>r<span class="token punctuation">,</span> d<span class="token punctuation">));</span>
|
||
<span class="token function">runPromisesInSeries</span><span class="token punctuation">([()</span> <span class="token operator">=></span> <span class="token function">delay</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">), ()</span> <span class="token operator">=></span> <span class="token function">delay</span><span class="token punctuation">(</span><span class="token number">2000</span><span class="token punctuation">)]);</span> <span class="token comment">// Executes each promise sequentially, taking a total of 3 seconds to complete</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sleep" class="section double-padded">sleep</h3><div class="section double-padded"><p>Delays the execution of an asynchronous function.</p><p>Delay executing part of an <code>async</code> function, by putting it to sleep, returning a <code>Promise</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sleep</span> <span class="token operator">=</span> ms <span class="token operator">=></span> <span class="token keyword">new</span> <span class="token class-name">Promise</span><span class="token punctuation">(</span>resolve <span class="token operator">=></span> <span class="token function">setTimeout</span><span class="token punctuation">(</span>resolve<span class="token punctuation">,</span> ms<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">async function</span> <span class="token function">sleepyWork</span><span class="token punctuation">() {</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">"I'm going to sleep for 1 second."</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">await</span> <span class="token function">sleep</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">);</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'I woke up after 1 second.'</span><span class="token punctuation">);
|
||
}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Math</h2><div class="card fluid"><h3 id="average" class="section double-padded">average</h3><div class="section double-padded"><p>Returns the average of an of two or more numbers.</p><p>Use <code>Array.reduce()</code> to add each value to an accumulator, initialized with a value of <code>0</code>, divide by the <code>length</code> of the array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">average</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>nums<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>nums<span class="token punctuation">].</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">/</span> nums<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">average</span><span class="token punctuation">(</span><span class="token operator">...</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]);</span> <span class="token comment">// 2</span>
|
||
<span class="token function">average</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// 2</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="averageby" class="section double-padded">averageBy</h3><div class="section double-padded"><p>Returns the average of an array, after mapping each element to a value using the provided function.</p><p>Use <code>Array.map()</code> to map each element to the value returned by <code>fn</code>, <code>Array.reduce()</code> to add each value to an accumulator, initialized with a value of <code>0</code>, divide by the <code>length</code> of the array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">averageBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> fn <span class="token operator">===</span> <span class="token string">'function'</span> <span class="token operator">?</span> fn <span class="token punctuation">:</span> val <span class="token operator">=></span> val<span class="token punctuation">[</span>fn<span class="token punctuation">]).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">/</span>
|
||
arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">averageBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> o <span class="token operator">=></span> o<span class="token punctuation">.</span>n<span class="token punctuation">);</span> <span class="token comment">// 5</span>
|
||
<span class="token function">averageBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> <span class="token string">'n'</span><span class="token punctuation">);</span> <span class="token comment">// 5</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="clampnumber" class="section double-padded">clampNumber</h3><div class="section double-padded"><p>Clamps <code>num</code> within the inclusive range specified by the boundary values <code>a</code> and <code>b</code>.</p><p>If <code>num</code> falls within the range, return <code>num</code>. Otherwise, return the nearest number in the range.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">clampNumber</span> <span class="token operator">=</span> <span class="token punctuation">(</span>num<span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">min</span><span class="token punctuation">(</span>num<span class="token punctuation">,</span> Math<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)),</span> Math<span class="token punctuation">.</span><span class="token function">min</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">clampNumber</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// 3</span>
|
||
<span class="token function">clampNumber</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// -1</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="digitize" class="section double-padded">digitize</h3><div class="section double-padded"><p>Converts a number to an array of digits.</p><p>Convert the number to a string, using the spread operator (<code>...</code>) to build an array. Use <code>Array.map()</code> and <code>parseInt()</code> to transform each value to an integer.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">digitize</span> <span class="token operator">=</span> n <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span><span class="token template-string"><span class="token string">`</span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>n<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">`</span></span><span class="token punctuation">].</span><span class="token function">map</span><span class="token punctuation">(</span>i <span class="token operator">=></span> <span class="token function">parseInt</span><span class="token punctuation">(</span>i<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">digitize</span><span class="token punctuation">(</span><span class="token number">123</span><span class="token punctuation">);</span> <span class="token comment">// [1, 2, 3]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="distance" class="section double-padded">distance</h3><div class="section double-padded"><p>Returns the distance between two points.</p><p>Use <code>Math.hypot()</code> to calculate the Euclidean distance between two points.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">distance</span> <span class="token operator">=</span> <span class="token punctuation">(</span>x0<span class="token punctuation">,</span> y0<span class="token punctuation">,</span> x1<span class="token punctuation">,</span> y1<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">hypot</span><span class="token punctuation">(</span>x1 <span class="token operator">-</span> x0<span class="token punctuation">,</span> y1 <span class="token operator">-</span> y0<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">distance</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// 2.23606797749979</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="elo" class="section double-padded">elo<mark class="tag">advanced</mark></h3><div class="section double-padded"><p>Computes the new ratings between two or more opponents using the <a href="https://en.wikipedia.org/wiki/Elo_rating_system">Elo rating system</a>. It takes an array of pre-ratings and returns an array containing post-ratings. The array should be ordered from best performer to worst performer (winner -> loser).</p><p>Use the exponent <code>**</code> operator and math operators to compute the expected score (chance of winning). of each opponent and compute the new rating for each. Loop through the ratings, using each permutation to compute the post-Elo rating for each player in a pairwise fashion. Omit the second argument to use the default <code>kFactor</code> of 32.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">elo</span> <span class="token operator">=</span> <span class="token punctuation">([</span><span class="token operator">...</span>ratings<span class="token punctuation">],</span> kFactor <span class="token operator">=</span> <span class="token number">32</span><span class="token punctuation">,</span> selfRating<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> <span class="token punctuation">[</span>a<span class="token punctuation">,</span> b<span class="token punctuation">]</span> <span class="token operator">=</span> ratings<span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">expectedScore</span> <span class="token operator">=</span> <span class="token punctuation">(</span>self<span class="token punctuation">,</span> opponent<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token number">1</span> <span class="token operator">/</span> <span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">+</span> <span class="token number">10</span> <span class="token operator">**</span> <span class="token punctuation">((</span>opponent <span class="token operator">-</span> self<span class="token punctuation">)</span> <span class="token operator">/</span> <span class="token number">400</span><span class="token punctuation">));</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">newRating</span> <span class="token operator">=</span> <span class="token punctuation">(</span>rating<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span>selfRating <span class="token operator">||</span> rating<span class="token punctuation">)</span> <span class="token operator">+</span> kFactor <span class="token operator">*</span> <span class="token punctuation">(</span>i <span class="token operator">-</span> <span class="token function">expectedScore</span><span class="token punctuation">(</span>i <span class="token operator">?</span> a <span class="token punctuation">:</span> b<span class="token punctuation">,</span> i <span class="token operator">?</span> b <span class="token punctuation">:</span> a<span class="token punctuation">));</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>ratings<span class="token punctuation">.</span>length <span class="token operator">===</span> <span class="token number">2</span><span class="token punctuation">) {</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token function">newRating</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">),</span> <span class="token function">newRating</span><span class="token punctuation">(</span>b<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)];
|
||
}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> ratings<span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">) {</span>
|
||
<span class="token keyword">let</span> j <span class="token operator">=</span> i<span class="token punctuation">;</span>
|
||
<span class="token keyword">while</span> <span class="token punctuation">(</span>j <span class="token operator"><</span> ratings<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">) {
|
||
[</span>ratings<span class="token punctuation">[</span>i<span class="token punctuation">],</span> ratings<span class="token punctuation">[</span>j <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">]]</span> <span class="token operator">=</span> <span class="token function">elo</span><span class="token punctuation">([</span>ratings<span class="token punctuation">[</span>i<span class="token punctuation">],</span> ratings<span class="token punctuation">[</span>j <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">]],</span> kFactor<span class="token punctuation">);</span>
|
||
j<span class="token operator">++</span><span class="token punctuation">;
|
||
}
|
||
}
|
||
}</span>
|
||
<span class="token keyword">return</span> ratings<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token comment">// Standard 1v1s</span>
|
||
<span class="token function">elo</span><span class="token punctuation">([</span><span class="token number">1200</span><span class="token punctuation">,</span> <span class="token number">1200</span><span class="token punctuation">]);</span> <span class="token comment">// [1216, 1184]</span>
|
||
<span class="token function">elo</span><span class="token punctuation">([</span><span class="token number">1200</span><span class="token punctuation">,</span> <span class="token number">1200</span><span class="token punctuation">],</span> <span class="token number">64</span><span class="token punctuation">);</span> <span class="token comment">// [1232, 1168]</span>
|
||
<span class="token comment">// 4 player FFA, all same rank</span>
|
||
<span class="token function">elo</span><span class="token punctuation">([</span><span class="token number">1200</span><span class="token punctuation">,</span> <span class="token number">1200</span><span class="token punctuation">,</span> <span class="token number">1200</span><span class="token punctuation">,</span> <span class="token number">1200</span><span class="token punctuation">]).</span><span class="token function">map</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span>round<span class="token punctuation">);</span> <span class="token comment">// [1246, 1215, 1185, 1154]</span>
|
||
<span class="token comment">/*
|
||
For teams, each rating can adjusted based on own team's average rating vs.
|
||
average rating of opposing team, with the score being added to their
|
||
own individual rating by supplying it as the third argument.
|
||
*/</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="factorial" class="section double-padded">factorial</h3><div class="section double-padded"><p>Calculates the factorial of a number.</p><p>Use recursion. If <code>n</code> is less than or equal to <code>1</code>, return <code>1</code>. Otherwise, return the product of <code>n</code> and the factorial of <code>n - 1</code>. Throws an exception if <code>n</code> is a negative number.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">factorial</span> <span class="token operator">=</span> n <span class="token operator">=></span>
|
||
n <span class="token operator"><</span> <span class="token number">0</span>
|
||
<span class="token operator">?</span> <span class="token punctuation">(()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">throw new</span> <span class="token class-name">TypeError</span><span class="token punctuation">(</span><span class="token string">'Negative numbers are not allowed!'</span><span class="token punctuation">);
|
||
})()
|
||
:</span> n <span class="token operator"><=</span> <span class="token number">1</span> <span class="token operator">?</span> <span class="token number">1</span> <span class="token punctuation">:</span> n <span class="token operator">*</span> <span class="token function">factorial</span><span class="token punctuation">(</span>n <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">factorial</span><span class="token punctuation">(</span><span class="token number">6</span><span class="token punctuation">);</span> <span class="token comment">// 720</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="fibonacci" class="section double-padded">fibonacci</h3><div class="section double-padded"><p>Generates an array, containing the Fibonacci sequence, up until the nth term.</p><p>Create an empty array of the specific length, initializing the first two values (<code>0</code> and <code>1</code>). Use <code>Array.reduce()</code> to add values into the array, using the sum of the last two values, except for the first two.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">fibonacci</span> <span class="token operator">=</span> n <span class="token operator">=></span>
|
||
Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> n <span class="token punctuation">}).</span><span class="token function">reduce</span><span class="token punctuation">(
|
||
(</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> acc<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>i <span class="token operator">></span> <span class="token number">1</span> <span class="token operator">?</span> acc<span class="token punctuation">[</span>i <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">+</span> acc<span class="token punctuation">[</span>i <span class="token operator">-</span> <span class="token number">2</span><span class="token punctuation">] :</span> i<span class="token punctuation">),
|
||
[]
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">fibonacci</span><span class="token punctuation">(</span><span class="token number">6</span><span class="token punctuation">);</span> <span class="token comment">// [0, 1, 1, 2, 3, 5]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="gcd" class="section double-padded">gcd</h3><div class="section double-padded"><p>Calculates the greatest common divisor between two or more numbers/arrays.</p><p>The inner <code>_gcd</code> function uses recursion. Base case is when <code>y</code> equals <code>0</code>. In this case, return <code>x</code>. Otherwise, return the GCD of <code>y</code> and the remainder of the division <code>x/y</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">gcd</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">_gcd</span> <span class="token operator">=</span> <span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">!</span>y <span class="token operator">?</span> x <span class="token punctuation">:</span> <span class="token function">gcd</span><span class="token punctuation">(</span>y<span class="token punctuation">,</span> x <span class="token operator">%</span> y<span class="token punctuation">));</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">_gcd</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">));
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">gcd</span><span class="token punctuation">(</span><span class="token number">8</span><span class="token punctuation">,</span> <span class="token number">36</span><span class="token punctuation">);</span> <span class="token comment">// 4</span>
|
||
<span class="token function">gcd</span><span class="token punctuation">(</span><span class="token operator">...</span><span class="token punctuation">[</span><span class="token number">12</span><span class="token punctuation">,</span> <span class="token number">8</span><span class="token punctuation">,</span> <span class="token number">32</span><span class="token punctuation">]);</span> <span class="token comment">// 4</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="geometricprogression" class="section double-padded">geometricProgression</h3><div class="section double-padded"><p>Initializes an array containing the numbers in the specified range where <code>start</code> and <code>end</code> are inclusive and the ratio between two terms is <code>step</code>. Returns an error if <code>step</code> equals <code>1</code>.</p><p>Use <code>Array.from()</code>, <code>Math.log()</code> and <code>Math.floor()</code> to create an array of the desired length, <code>Array.map()</code> to fill with the desired values in a range. Omit the second argument, <code>start</code>, to use a default value of <code>1</code>. Omit the third argument, <code>step</code>, to use a default value of <code>2</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">geometricProgression</span> <span class="token operator">=</span> <span class="token punctuation">(</span>end<span class="token punctuation">,</span> start <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">,</span> step <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token operator">=></span>
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||
Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>end <span class="token operator">/</span> start<span class="token punctuation">)</span> <span class="token operator">/</span> Math<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>step<span class="token punctuation">))</span> <span class="token operator">+</span> <span class="token number">1</span> <span class="token punctuation">}).</span><span class="token function">map</span><span class="token punctuation">(
|
||
(</span>v<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> start <span class="token operator">*</span> step <span class="token operator">**</span> i
|
||
<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">geometricProgression</span><span class="token punctuation">(</span><span class="token number">256</span><span class="token punctuation">);</span> <span class="token comment">// [1, 2, 4, 8, 16, 32, 64, 128, 256]</span>
|
||
<span class="token function">geometricProgression</span><span class="token punctuation">(</span><span class="token number">256</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// [3, 6, 12, 24, 48, 96, 192]</span>
|
||
<span class="token function">geometricProgression</span><span class="token punctuation">(</span><span class="token number">256</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">);</span> <span class="token comment">// [1, 4, 16, 64, 256]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="hammingdistance" class="section double-padded">hammingDistance</h3><div class="section double-padded"><p>Calculates the Hamming distance between two values.</p><p>Use XOR operator (<code>^</code>) to find the bit difference between the two numbers, convert to a binary string using <code>toString(2)</code>. Count and return the number of <code>1</code>s in the string, using <code>match(/1/g)</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">hammingDistance</span> <span class="token operator">=</span> <span class="token punctuation">(</span>num1<span class="token punctuation">,</span> num2<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">((</span>num1 <span class="token operator">^</span> num2<span class="token punctuation">).</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">).</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex">/1/g</span><span class="token punctuation">)</span> <span class="token operator">||</span> <span class="token string">''</span><span class="token punctuation">).</span>length<span class="token punctuation">;</span>
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||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">hammingDistance</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// 1</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="inrange" class="section double-padded">inRange</h3><div class="section double-padded"><p>Checks if the given number falls within the given range.</p><p>Use arithmetic comparison to check if the given number is in the specified range. If the second parameter, <code>end</code>, is not specified, the range is considered to be from <code>0</code> to <code>start</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">inRange</span> <span class="token operator">=</span> <span class="token punctuation">(</span>n<span class="token punctuation">,</span> start<span class="token punctuation">,</span> end <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
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||
<span class="token keyword">if</span> <span class="token punctuation">(</span>end <span class="token operator">&&</span> start <span class="token operator">></span> end<span class="token punctuation">)</span> end <span class="token operator">=</span> <span class="token punctuation">[</span>start<span class="token punctuation">, (</span>start <span class="token operator">=</span> end<span class="token punctuation">)][</span><span class="token number">0</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">return</span> end <span class="token operator">==</span> <span class="token keyword">null</span> <span class="token operator">?</span> n <span class="token operator">>=</span> <span class="token number">0</span> <span class="token operator">&&</span> n <span class="token operator"><</span> start <span class="token punctuation">:</span> n <span class="token operator">>=</span> start <span class="token operator">&&</span> n <span class="token operator"><</span> end<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">inRange</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">inRange</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">inRange</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">inrange</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isdivisible" class="section double-padded">isDivisible</h3><div class="section double-padded"><p>Checks if the first numeric argument is divisible by the second one.</p><p>Use the modulo operator (<code>%</code>) to check if the remainder is equal to <code>0</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isDivisible</span> <span class="token operator">=</span> <span class="token punctuation">(</span>dividend<span class="token punctuation">,</span> divisor<span class="token punctuation">)</span> <span class="token operator">=></span> dividend <span class="token operator">%</span> divisor <span class="token operator">===</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isDivisible</span><span class="token punctuation">(</span><span class="token number">6</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="iseven" class="section double-padded">isEven</h3><div class="section double-padded"><p>Returns <code>true</code> if the given number is even, <code>false</code> otherwise.</p><p>Checks whether a number is odd or even using the modulo (<code>%</code>) operator. Returns <code>true</code> if the number is even, <code>false</code> if the number is odd.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isEven</span> <span class="token operator">=</span> num <span class="token operator">=></span> num <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">===</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isEven</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isprime" class="section double-padded">isPrime</h3><div class="section double-padded"><p>Checks if the provided integer is a prime number.</p><p>Check numbers from <code>2</code> to the square root of the given number. Return <code>false</code> if any of them divides the given number, else return <code>true</code>, unless the number is less than <code>2</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isPrime</span> <span class="token operator">=</span> num <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> boundary <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">sqrt</span><span class="token punctuation">(</span>num<span class="token punctuation">));</span>
|
||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">var</span> i <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">;</span> i <span class="token operator"><=</span> boundary<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>num <span class="token operator">%</span> i <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> num <span class="token operator">>=</span> <span class="token number">2</span><span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isPrime</span><span class="token punctuation">(</span><span class="token number">11</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="lcm" class="section double-padded">lcm</h3><div class="section double-padded"><p>Returns the least common multiple of two or more numbers.</p><p>Use the greatest common divisor (GCD) formula and the fact that <code>lcm(x,y) = x * y / gcd(x,y)</code> to determine the least common multiple. The GCD formula uses recursion.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">lcm</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">gcd</span> <span class="token operator">=</span> <span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">!</span>y <span class="token operator">?</span> x <span class="token punctuation">:</span> <span class="token function">gcd</span><span class="token punctuation">(</span>y<span class="token punctuation">,</span> x <span class="token operator">%</span> y<span class="token punctuation">));</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">_lcm</span> <span class="token operator">=</span> <span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">)</span> <span class="token operator">=></span> x <span class="token operator">*</span> y <span class="token operator">/</span> <span class="token function">gcd</span><span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">_lcm</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">));
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">lcm</span><span class="token punctuation">(</span><span class="token number">12</span><span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">);</span> <span class="token comment">// 84</span>
|
||
<span class="token function">lcm</span><span class="token punctuation">(</span><span class="token operator">...</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// 60</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="luhncheck" class="section double-padded">luhnCheck</h3><div class="section double-padded"><p>Implementation of the <a href="https://en.wikipedia.org/wiki/Luhn_algorithm">Luhn Algorithm</a> used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identifier numbers etc.</p><p>Use <code>String.split('')</code>, <code>Array.reverse()</code> and <code>Array.map()</code> in combination with <code>parseInt()</code> to obtain an array of digits. Use <code>Array.splice(0,1)</code> to obtain the last digit. Use <code>Array.reduce()</code> to implement the Luhn Algorithm. Return <code>true</code> if <code>sum</code> is divisible by <code>10</code>, <code>false</code> otherwise.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">luhnCheck</span> <span class="token operator">=</span> num <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> arr <span class="token operator">=</span> <span class="token punctuation">(</span>num <span class="token operator">+</span> <span class="token string">''</span><span class="token punctuation">)
|
||
.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">)
|
||
.</span><span class="token function">reverse</span><span class="token punctuation">()
|
||
.</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> <span class="token function">parseInt</span><span class="token punctuation">(</span>x<span class="token punctuation">));</span>
|
||
<span class="token keyword">let</span> lastDigit <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)[</span><span class="token number">0</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">let</span> sum <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>i <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">!==</span> <span class="token number">0</span> <span class="token operator">?</span> acc <span class="token operator">+</span> val <span class="token punctuation">:</span> acc <span class="token operator">+</span> <span class="token punctuation">(</span>val <span class="token operator">*</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">9</span> <span class="token operator">||</span> <span class="token number">9</span><span class="token punctuation">),</span> <span class="token number">0</span><span class="token punctuation">);</span>
|
||
sum <span class="token operator">+=</span> lastDigit<span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> sum <span class="token operator">%</span> <span class="token number">10</span> <span class="token operator">===</span> <span class="token number">0</span><span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">luhnCheck</span><span class="token punctuation">(</span><span class="token string">'4485275742308327'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">luhnCheck</span><span class="token punctuation">(</span><span class="token number">6011329933655299</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">luhnCheck</span><span class="token punctuation">(</span><span class="token number">123456789</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="maxby" class="section double-padded">maxBy</h3><div class="section double-padded"><p>Returns the maximum value of an array, after mapping each element to a value using the provided function.</p><p>Use <code>Array.map()</code> to map each element to the value returned by <code>fn</code>, <code>Math.max()</code> to get the maximum value.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">maxBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> fn <span class="token operator">===</span> <span class="token string">'function'</span> <span class="token operator">?</span> fn <span class="token punctuation">:</span> val <span class="token operator">=></span> val<span class="token punctuation">[</span>fn<span class="token punctuation">]));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">maxBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> o <span class="token operator">=></span> o<span class="token punctuation">.</span>n<span class="token punctuation">);</span> <span class="token comment">// 8</span>
|
||
<span class="token function">maxBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> <span class="token string">'n'</span><span class="token punctuation">);</span> <span class="token comment">// 8</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="median" class="section double-padded">median</h3><div class="section double-padded"><p>Returns the median of an array of numbers.</p><p>Find the middle of the array, use <code>Array.sort()</code> to sort the values. Return the number at the midpoint if <code>length</code> is odd, otherwise the average of the two middle numbers.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">median</span> <span class="token operator">=</span> arr <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> mid <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">),</span>
|
||
nums <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">sort</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> a <span class="token operator">-</span> b<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> arr<span class="token punctuation">.</span>length <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">!==</span> <span class="token number">0</span> <span class="token operator">?</span> nums<span class="token punctuation">[</span>mid<span class="token punctuation">] : (</span>nums<span class="token punctuation">[</span>mid <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">+</span> nums<span class="token punctuation">[</span>mid<span class="token punctuation">])</span> <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">median</span><span class="token punctuation">([</span><span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token punctuation">,</span> <span class="token number">50</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// 5</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="minby" class="section double-padded">minBy</h3><div class="section double-padded"><p>Returns the minimum value of an array, after mapping each element to a value using the provided function.</p><p>Use <code>Array.map()</code> to map each element to the value returned by <code>fn</code>, <code>Math.min()</code> to get the maximum value.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">minBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">min</span><span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> fn <span class="token operator">===</span> <span class="token string">'function'</span> <span class="token operator">?</span> fn <span class="token punctuation">:</span> val <span class="token operator">=></span> val<span class="token punctuation">[</span>fn<span class="token punctuation">]));</span>
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||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">minBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> o <span class="token operator">=></span> o<span class="token punctuation">.</span>n<span class="token punctuation">);</span> <span class="token comment">// 8</span>
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||
<span class="token function">minBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> <span class="token string">'n'</span><span class="token punctuation">);</span> <span class="token comment">// 8</span>
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||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="percentile" class="section double-padded">percentile</h3><div class="section double-padded"><p>Uses the percentile formula to calculate how many numbers in the given array are less or equal to the given value.</p><p>Use <code>Array.reduce()</code> to calculate how many numbers are below the value and how many are the same value and apply the percentile formula.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">percentile</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span>
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||
<span class="token number">100</span> <span class="token operator">*</span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> <span class="token punctuation">(</span>v <span class="token operator"><</span> val <span class="token operator">?</span> <span class="token number">1</span> <span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token punctuation">(</span>v <span class="token operator">===</span> val <span class="token operator">?</span> <span class="token number">0.5</span> <span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">),</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">/</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
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</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">percentile</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">,</span> <span class="token number">8</span><span class="token punctuation">,</span> <span class="token number">9</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">],</span> <span class="token number">6</span><span class="token punctuation">);</span> <span class="token comment">// 55</span>
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||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="powerset" class="section double-padded">powerset</h3><div class="section double-padded"><p>Returns the powerset of a given array of numbers.</p><p>Use <code>Array.reduce()</code> combined with <code>Array.map()</code> to iterate over elements and combine into an array containing all combinations.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">powerset</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> a<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>r <span class="token operator">=></span> <span class="token punctuation">[</span>v<span class="token punctuation">].</span><span class="token function">concat</span><span class="token punctuation">(</span>r<span class="token punctuation">))), [[]]);</span>
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||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">powerset</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]);</span> <span class="token comment">// [[], [1], [2], [2,1]]</span>
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||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="primes" class="section double-padded">primes</h3><div class="section double-padded"><p>Generates primes up to a given number, using the Sieve of Eratosthenes.</p><p>Generate an array from <code>2</code> to the given number. Use <code>Array.filter()</code> to filter out the values divisible by any number from <code>2</code> to the square root of the provided number.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">primes</span> <span class="token operator">=</span> num <span class="token operator">=></span> <span class="token punctuation">{</span>
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||
<span class="token keyword">let</span> arr <span class="token operator">=</span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> num <span class="token operator">-</span> <span class="token number">1</span> <span class="token punctuation">}).</span><span class="token function">map</span><span class="token punctuation">((</span>x<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> i <span class="token operator">+</span> <span class="token number">2</span><span class="token punctuation">),</span>
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||
sqroot <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">sqrt</span><span class="token punctuation">(</span>num<span class="token punctuation">)),</span>
|
||
numsTillSqroot <span class="token operator">=</span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">({</span> length<span class="token punctuation">:</span> sqroot <span class="token operator">-</span> <span class="token number">1</span> <span class="token punctuation">}).</span><span class="token function">map</span><span class="token punctuation">((</span>x<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> i <span class="token operator">+</span> <span class="token number">2</span><span class="token punctuation">);</span>
|
||
numsTillSqroot<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>x <span class="token operator">=></span> <span class="token punctuation">(</span>arr <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>y <span class="token operator">=></span> y <span class="token operator">%</span> x <span class="token operator">!==</span> <span class="token number">0</span> <span class="token operator">||</span> y <span class="token operator">==</span> x<span class="token punctuation">)));</span>
|
||
<span class="token keyword">return</span> arr<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">primes</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">);</span> <span class="token comment">// [2,3,5,7]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="randomintegerinrange" class="section double-padded">randomIntegerInRange</h3><div class="section double-padded"><p>Returns a random integer in the specified range.</p><p>Use <code>Math.random()</code> to generate a random number and map it to the desired range, using <code>Math.floor()</code> to make it an integer.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">randomIntegerInRange</span> <span class="token operator">=</span> <span class="token punctuation">(</span>min<span class="token punctuation">,</span> max<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> <span class="token punctuation">(</span>max <span class="token operator">-</span> min <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">))</span> <span class="token operator">+</span> min<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">randomIntegerInRange</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// 2</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="randomnumberinrange" class="section double-padded">randomNumberInRange</h3><div class="section double-padded"><p>Returns a random number in the specified range.</p><p>Use <code>Math.random()</code> to generate a random value, map it to the desired range using multiplication.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">randomNumberInRange</span> <span class="token operator">=</span> <span class="token punctuation">(</span>min<span class="token punctuation">,</span> max<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> <span class="token punctuation">(</span>max <span class="token operator">-</span> min<span class="token punctuation">)</span> <span class="token operator">+</span> min<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">randomNumberInRange</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">);</span> <span class="token comment">// 6.0211363285087005</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="round" class="section double-padded">round</h3><div class="section double-padded"><p>Rounds a number to a specified amount of digits.</p><p>Use <code>Math.round()</code> and template literals to round the number to the specified number of digits. Omit the second argument, <code>decimals</code> to round to an integer.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">round</span> <span class="token operator">=</span> <span class="token punctuation">(</span>n<span class="token punctuation">,</span> decimals <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">Number</span><span class="token punctuation">(</span><span class="token template-string"><span class="token string">`${Math.round(`</span></span>$<span class="token punctuation">{</span>n<span class="token punctuation">}</span>e$<span class="token punctuation">{</span>decimals<span class="token punctuation">}</span><span class="token template-string"><span class="token string">`)}e-</span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>decimals<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">`</span></span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">round</span><span class="token punctuation">(</span><span class="token number">1.005</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">);</span> <span class="token comment">// 1.01</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sdbm" class="section double-padded">sbdm</h3><div class="section double-padded"><p>Hashes the input string into a whole number.</p><p>Use <code>String.split('')</code> and <code>Array.reduce()</code> to create a hash of the input string, utilizing bit shifting.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sdbm</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> arr <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(
|
||
(</span>hashCode<span class="token punctuation">,</span> currentVal<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span>hashCode <span class="token operator">=</span> currentVal<span class="token punctuation">.</span><span class="token function">charCodeAt</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token punctuation">(</span>hashCode <span class="token operator"><<</span> <span class="token number">6</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token punctuation">(</span>hashCode <span class="token operator"><<</span> <span class="token number">16</span><span class="token punctuation">)</span> <span class="token operator">-</span> hashCode<span class="token punctuation">),</span>
|
||
<span class="token number">0</span>
|
||
<span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sdbm</span><span class="token punctuation">(</span><span class="token string">'name'</span><span class="token punctuation">);</span> <span class="token comment">// -3521204949</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="standarddeviation" class="section double-padded">standardDeviation</h3><div class="section double-padded"><p>Returns the standard deviation of an array of numbers.</p><p>Use <code>Array.reduce()</code> to calculate the mean, variance and the sum of the variance of the values, the variance of the values, then determine the standard deviation. You can omit the second argument to get the sample standard deviation or set it to <code>true</code> to get the population standard deviation.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">standardDeviation</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> usePopulation <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> mean <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">/</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> Math<span class="token punctuation">.</span><span class="token function">sqrt</span><span class="token punctuation">(</span>
|
||
arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">((</span>val <span class="token operator">-</span> mean<span class="token punctuation">)</span> <span class="token operator">**</span> <span class="token number">2</span><span class="token punctuation">), []).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">/</span>
|
||
<span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token punctuation">(</span>usePopulation <span class="token operator">?</span> <span class="token number">0</span> <span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">))
|
||
);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">standardDeviation</span><span class="token punctuation">([</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">]);</span> <span class="token comment">// 13.284434142114991 (sample)</span>
|
||
<span class="token function">standardDeviation</span><span class="token punctuation">([</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">],</span> <span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// 12.29899614287479 (population)</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sum" class="section double-padded">sum</h3><div class="section double-padded"><p>Returns the sum of two or more numbers/arrays.</p><p>Use <code>Array.reduce()</code> to add each value to an accumulator, initialized with a value of <code>0</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sum</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sum</span><span class="token punctuation">(</span><span class="token operator">...</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]);</span> <span class="token comment">// 10</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sumby" class="section double-padded">sumBy</h3><div class="section double-padded"><p>Returns the sum of an array, after mapping each element to a value using the provided function.</p><p>Use <code>Array.map()</code> to map each element to the value returned by <code>fn</code>, <code>Array.reduce()</code> to add each value to an accumulator, initialized with a value of <code>0</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sumBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> fn <span class="token operator">===</span> <span class="token string">'function'</span> <span class="token operator">?</span> fn <span class="token punctuation">:</span> val <span class="token operator">=></span> val<span class="token punctuation">[</span>fn<span class="token punctuation">]).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sumBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> o <span class="token operator">=></span> o<span class="token punctuation">.</span>n<span class="token punctuation">);</span> <span class="token comment">// 20</span>
|
||
<span class="token function">sumBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> <span class="token string">'n'</span><span class="token punctuation">);</span> <span class="token comment">// 20</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sumpower" class="section double-padded">sumPower</h3><div class="section double-padded"><p>Returns the sum of the powers of all the numbers from <code>start</code> to <code>end</code> (both inclusive).</p><p>Use <code>Array.fill()</code> to create an array of all the numbers in the target range, <code>Array.map()</code> and the exponent operator (<code>**</code>) to raise them to <code>power</code> and <code>Array.reduce()</code> to add them together. Omit the second argument, <code>power</code>, to use a default power of <code>2</code>. Omit the third argument, <code>start</code>, to use a default starting value of <code>1</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sumPower</span> <span class="token operator">=</span> <span class="token punctuation">(</span>end<span class="token punctuation">,</span> power <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">,</span> start <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token function">Array</span><span class="token punctuation">(</span>end <span class="token operator">+</span> <span class="token number">1</span> <span class="token operator">-</span> start<span class="token punctuation">)
|
||
.</span><span class="token function">fill</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)
|
||
.</span><span class="token function">map</span><span class="token punctuation">((</span>x<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span>i <span class="token operator">+</span> start<span class="token punctuation">)</span> <span class="token operator">**</span> power<span class="token punctuation">)
|
||
.</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> a <span class="token operator">+</span> b<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sumPower</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">);</span> <span class="token comment">// 385</span>
|
||
<span class="token function">sumPower</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">//3025</span>
|
||
<span class="token function">sumPower</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">//2925</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="tosafeinteger" class="section double-padded">toSafeInteger</h3><div class="section double-padded"><p>Converts a value to a safe integer.</p><p>Use <code>Math.max()</code> and <code>Math.min()</code> to find the closest safe value. Use <code>Math.round()</code> to convert to an integer.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">toSafeInteger</span> <span class="token operator">=</span> num <span class="token operator">=></span>
|
||
Math<span class="token punctuation">.</span><span class="token function">round</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">min</span><span class="token punctuation">(</span>num<span class="token punctuation">,</span> Number<span class="token punctuation">.</span>MAX_SAFE_INTEGER<span class="token punctuation">),</span> Number<span class="token punctuation">.</span>MIN_SAFE_INTEGER<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">toSafeInteger</span><span class="token punctuation">(</span><span class="token string">'3.2'</span><span class="token punctuation">);</span> <span class="token comment">// 3</span>
|
||
<span class="token function">toSafeInteger</span><span class="token punctuation">(</span><span class="token number">Infinity</span><span class="token punctuation">);</span> <span class="token comment">// 9007199254740991</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Node</h2><div class="card fluid"><h3 id="hasflags" class="section double-padded">hasFlags</h3><div class="section double-padded"><p>Check if the current process's arguments contain the specified flags.</p><p>Use <code>Array.every()</code> and <code>Array.includes()</code> to check if <code>process.argv</code> contains all the specified flags. Use a regular expression to test if the specified flags are prefixed with <code>-</code> or <code>--</code> and prefix them accordingly.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">hasFlags</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>flags<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
flags<span class="token punctuation">.</span><span class="token function">every</span><span class="token punctuation">(</span>flag <span class="token operator">=></span> process<span class="token punctuation">.</span>argv<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span><span class="token regex">/^-{1,2}/</span><span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>flag<span class="token punctuation">)</span> <span class="token operator">?</span> flag <span class="token punctuation">:</span> <span class="token string">'--'</span> <span class="token operator">+</span> flag<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token comment">// node myScript.js -s --test --cool=true</span>
|
||
<span class="token function">hasFlags</span><span class="token punctuation">(</span><span class="token string">'-s'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">hasFlags</span><span class="token punctuation">(</span><span class="token string">'--test'</span><span class="token punctuation">,</span> <span class="token string">'cool=true'</span><span class="token punctuation">,</span> <span class="token string">'-s'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">hasFlags</span><span class="token punctuation">(</span><span class="token string">'special'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="istravisci" class="section double-padded">isTravisCI</h3><div class="section double-padded"><p>Checks if the current environment is <a href="https://travis-ci.org/">Travis CI</a>.</p><p>Checks if the current environment has the <code>TRAVIS</code> and <code>CI</code> environment variables (<a href="https://docs.travis-ci.com/user/environment-variables/#Default-Environment-Variables">reference</a>).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isTravisCI</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token string">'TRAVIS'</span> <span class="token keyword">in</span> process<span class="token punctuation">.</span>env <span class="token operator">&&</span> <span class="token string">'CI'</span> <span class="token keyword">in</span> process<span class="token punctuation">.</span>env<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isTravisCI</span><span class="token punctuation">();</span> <span class="token comment">// true (if code is running on Travis CI)</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="jsontofile" class="section double-padded">JSONToFile</h3><div class="section double-padded"><p>Writes a JSON object to a file.</p><p>Use <code>fs.writeFile()</code>, template literals and <code>JSON.stringify()</code> to write a <code>json</code> object to a <code>.json</code> file.</p><pre class="language-js"><span class="token keyword">const</span> fs <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'fs'</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">JSONToFile</span> <span class="token operator">=</span> <span class="token punctuation">(</span>obj<span class="token punctuation">,</span> filename<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
fs<span class="token punctuation">.</span><span class="token function">writeFile</span><span class="token punctuation">(</span><span class="token template-string"><span class="token string">`</span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>filename<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">.json`</span></span><span class="token punctuation">,</span> JSON<span class="token punctuation">.</span><span class="token function">stringify</span><span class="token punctuation">(</span>obj<span class="token punctuation">,</span> <span class="token keyword">null</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">JSONToFile</span><span class="token punctuation">({</span> test<span class="token punctuation">:</span> <span class="token string">'is passed'</span> <span class="token punctuation">},</span> <span class="token string">'testJsonFile'</span><span class="token punctuation">);</span> <span class="token comment">// writes the object to 'testJsonFile.json'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="readfilelines" class="section double-padded">readFileLines</h3><div class="section double-padded"><p>Returns an array of lines from the specified file.</p><p>Use <code>readFileSync</code> function in <code>fs</code> node package to create a <code>Buffer</code> from a file. convert buffer to string using <code>toString(encoding)</code> function. creating an array from contents of file by <code>split</code>ing file content line by line (each <code>\n</code>).</p><pre class="language-js"><span class="token keyword">const</span> fs <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'fs'</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">readFileLines</span> <span class="token operator">=</span> filename <span class="token operator">=></span>
|
||
fs
|
||
<span class="token punctuation">.</span><span class="token function">readFileSync</span><span class="token punctuation">(</span>filename<span class="token punctuation">)
|
||
.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token string">'UTF8'</span><span class="token punctuation">)
|
||
.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">'\n'</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token comment">/*
|
||
contents of test.txt :
|
||
line1
|
||
line2
|
||
line3
|
||
___________________________
|
||
*/</span>
|
||
<span class="token keyword">let</span> arr <span class="token operator">=</span> <span class="token function">readFileLines</span><span class="token punctuation">(</span><span class="token string">'test.txt'</span><span class="token punctuation">);</span>
|
||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>arr<span class="token punctuation">);</span> <span class="token comment">// ['line1', 'line2', 'line3']</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="untildify" class="section double-padded">untildify</h3><div class="section double-padded"><p>Converts a tilde path to an absolute path.</p><p>Use <code>String.replace()</code> with a regular expression and <code>OS.homedir()</code> to replace the <code>~</code> in the start of the path with the home directory.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">untildify</span> <span class="token operator">=</span> str <span class="token operator">=></span> str<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/^~($|\/|\\)/</span><span class="token punctuation">,</span> <span class="token template-string"><span class="token string">`</span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span><span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'os'</span><span class="token punctuation">).</span><span class="token function">homedir</span><span class="token punctuation">()</span><span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">$1`</span></span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">untildify</span><span class="token punctuation">(</span><span class="token string">'~/node'</span><span class="token punctuation">);</span> <span class="token comment">// '/Users/aUser/node'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="uuidgeneratornode" class="section double-padded">UUIDGeneratorNode</h3><div class="section double-padded"><p>Generates a UUID in Node.JS.</p><p>Use <code>crypto</code> API to generate a UUID, compliant with <a href="https://www.ietf.org/rfc/rfc4122.txt">RFC4122</a> version 4.</p><pre class="language-js"><span class="token keyword">const</span> crypto <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'crypto'</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">const</span> <span class="token function-variable function">UUIDGeneratorNode</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">([</span><span class="token number">1e7</span><span class="token punctuation">]</span> <span class="token operator">+ -</span><span class="token number">1e3</span> <span class="token operator">+ -</span><span class="token number">4e3</span> <span class="token operator">+ -</span><span class="token number">8e3</span> <span class="token operator">+ -</span><span class="token number">1e11</span><span class="token punctuation">).</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/[018]/g</span><span class="token punctuation">,</span> c <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span>c <span class="token operator">^</span> <span class="token punctuation">(</span>crypto<span class="token punctuation">.</span><span class="token function">randomBytes</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">&</span> <span class="token punctuation">(</span><span class="token number">15</span> <span class="token operator">>></span> <span class="token punctuation">(</span>c <span class="token operator">/</span> <span class="token number">4</span><span class="token punctuation">)))).</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token number">16</span><span class="token punctuation">)
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">UUIDGeneratorNode</span><span class="token punctuation">();</span> <span class="token comment">// '79c7c136-60ee-40a2-beb2-856f1feabefc'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Object</h2><div class="card fluid"><h3 id="cleanobj" class="section double-padded">cleanObj</h3><div class="section double-padded"><p>Removes any properties except the ones specified from a JSON object.</p><p>Use <code>Object.keys()</code> method to loop over given JSON object and deleting keys that are not included in given array. If you pass a special key,<code>childIndicator</code>, it will search deeply apply the function to inner objects, too.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">cleanObj</span> <span class="token operator">=</span> <span class="token punctuation">(</span>obj<span class="token punctuation">,</span> keysToKeep <span class="token operator">=</span> <span class="token punctuation">[],</span> childIndicator<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">forEach</span><span class="token punctuation">(</span>key <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>key <span class="token operator">===</span> childIndicator<span class="token punctuation">) {</span>
|
||
<span class="token function">cleanObj</span><span class="token punctuation">(</span>obj<span class="token punctuation">[</span>key<span class="token punctuation">],</span> keysToKeep<span class="token punctuation">,</span> childIndicator<span class="token punctuation">);
|
||
}</span> <span class="token keyword">else if</span> <span class="token punctuation">(</span><span class="token operator">!</span>keysToKeep<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>key<span class="token punctuation">)) {</span>
|
||
<span class="token keyword">delete</span> obj<span class="token punctuation">[</span>key<span class="token punctuation">];
|
||
}
|
||
});</span>
|
||
<span class="token keyword">return</span> obj<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> testObj <span class="token operator">=</span> <span class="token punctuation">{</span> a<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span> children<span class="token punctuation">: {</span> a<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">} };</span>
|
||
<span class="token function">cleanObj</span><span class="token punctuation">(</span>testObj<span class="token punctuation">, [</span><span class="token string">'a'</span><span class="token punctuation">],</span> <span class="token string">'children'</span><span class="token punctuation">);</span> <span class="token comment">// { a: 1, children : { a: 1}}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="functions" class="section double-padded">functions</h3><div class="section double-padded"><p>Returns an array of function property names from own (and optionally inherited) enumerable properties of an object.</p><p>Use <code>Object.keys(obj)</code> to iterate over the object's own properties. If <code>inherited</code> is <code>true</code>, use <code>Object.get.PrototypeOf(obj)</code> to also get the object's inherited properties. Use <code>Array.filter()</code> to keep only those properties that are functions. Omit the second argument, <code>inherited</code>, to not include inherited properties by default.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">functions</span> <span class="token operator">=</span> <span class="token punctuation">(</span>obj<span class="token punctuation">,</span> inherited <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span>inherited
|
||
<span class="token operator">?</span> <span class="token punctuation">[</span><span class="token operator">...</span>Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">),</span> <span class="token operator">...</span>Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>Object<span class="token punctuation">.</span><span class="token function">getPrototypeOf</span><span class="token punctuation">(</span>obj<span class="token punctuation">))]
|
||
:</span> Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">)
|
||
).</span><span class="token function">filter</span><span class="token punctuation">(</span>key <span class="token operator">=></span> <span class="token keyword">typeof</span> obj<span class="token punctuation">[</span>key<span class="token punctuation">]</span> <span class="token operator">===</span> <span class="token string">'function'</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">function</span> <span class="token function">Foo</span><span class="token punctuation">() {</span>
|
||
<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function-variable function">a</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token number">1</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function-variable function">b</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token number">2</span><span class="token punctuation">;
|
||
}</span>
|
||
Foo<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">c</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token number">3</span><span class="token punctuation">;</span>
|
||
<span class="token function">functions</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Foo</span><span class="token punctuation">());</span> <span class="token comment">// ['a', 'b']</span>
|
||
<span class="token function">functions</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Foo</span><span class="token punctuation">(),</span> <span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// ['a', 'b', 'c']</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="invertkeyvalues" class="section double-padded">invertKeyValues</h3><div class="section double-padded"><p>Inverts the key-value pairs of an object, without mutating it.</p><p>Use <code>Object.keys()</code> and <code>Array.reduce()</code> to invert the key-value pairs of an object.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">invertKeyValues</span> <span class="token operator">=</span> obj <span class="token operator">=></span>
|
||
Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> key<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span>obj<span class="token punctuation">[</span>key<span class="token punctuation">]]</span> <span class="token operator">=</span> key<span class="token punctuation">;</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">invertKeyValues</span><span class="token punctuation">({</span> name<span class="token punctuation">:</span> <span class="token string">'John'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">20</span> <span class="token punctuation">});</span> <span class="token comment">// { 20: 'age', John: 'name' }</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="lowercasekeys" class="section double-padded">lowercaseKeys</h3><div class="section double-padded"><p>Creates a new object from the specified object, where all the keys are in lowercase.</p><p>Use <code>Object.keys()</code> and <code>Array.reduce()</code> to create a new object from the specified object. Convert each key in the original object to lowercase, using <code>String.toLowerCase()</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">lowercaseKeys</span> <span class="token operator">=</span> obj <span class="token operator">=></span>
|
||
Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> key<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span>key<span class="token punctuation">.</span><span class="token function">toLowerCase</span><span class="token punctuation">()]</span> <span class="token operator">=</span> obj<span class="token punctuation">[</span>key<span class="token punctuation">];</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> myObj <span class="token operator">=</span> <span class="token punctuation">{</span> Name<span class="token punctuation">:</span> <span class="token string">'Adam'</span><span class="token punctuation">,</span> sUrnAME<span class="token punctuation">:</span> <span class="token string">'Smith'</span> <span class="token punctuation">};</span>
|
||
<span class="token keyword">const</span> myObjLower <span class="token operator">=</span> <span class="token function">lowercaseKeys</span><span class="token punctuation">(</span>myObj<span class="token punctuation">);</span> <span class="token comment">// {name: 'Adam', surname: 'Smith'};</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="mapkeys" class="section double-padded">mapKeys</h3><div class="section double-padded"><p>Creates an object with keys generated by running the provided function for each key and the same values as the provided object.</p><p>Use <code>Object.keys(obj)</code> to iterate over the object's keys. Use <code>Array.reduce()</code> to create a new object with the same values and mapped keys using <code>fn</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">mapKeys</span> <span class="token operator">=</span> <span class="token punctuation">(</span>obj<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> k<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span><span class="token function">fn</span><span class="token punctuation">(</span>obj<span class="token punctuation">[</span>k<span class="token punctuation">],</span> k<span class="token punctuation">,</span> obj<span class="token punctuation">)]</span> <span class="token operator">=</span> obj<span class="token punctuation">[</span>k<span class="token punctuation">];</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">mapKeys</span><span class="token punctuation">({</span> a<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, (</span>val<span class="token punctuation">,</span> key<span class="token punctuation">)</span> <span class="token operator">=></span> key <span class="token operator">+</span> val<span class="token punctuation">);</span> <span class="token comment">// { a1: 1, b2: 2 }</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="mapvalues" class="section double-padded">mapValues</h3><div class="section double-padded"><p>Creates an object with the same keys as the provided object and values generated by running the provided function for each value.</p><p>Use <code>Object.keys(obj)</code> to iterate over the object's keys. Use <code>Array.reduce()</code> to create a new object with the same keys and mapped values using <code>fn</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">mapValues</span> <span class="token operator">=</span> <span class="token punctuation">(</span>obj<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> k<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span>k<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token function">fn</span><span class="token punctuation">(</span>obj<span class="token punctuation">[</span>k<span class="token punctuation">],</span> k<span class="token punctuation">,</span> obj<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> users <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
fred<span class="token punctuation">: {</span> user<span class="token punctuation">:</span> <span class="token string">'fred'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">40</span> <span class="token punctuation">},</span>
|
||
pebbles<span class="token punctuation">: {</span> user<span class="token punctuation">:</span> <span class="token string">'pebbles'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">}
|
||
};</span>
|
||
<span class="token function">mapValues</span><span class="token punctuation">(</span>users<span class="token punctuation">,</span> u <span class="token operator">=></span> u<span class="token punctuation">.</span>age<span class="token punctuation">);</span> <span class="token comment">// { fred: 40, pebbles: 1 }</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="merge" class="section double-padded">merge</h3><div class="section double-padded"><p>Creates a new object from the combination of two or more objects.</p><p>Use <code>Array.reduce()</code> combined with <code>Object.keys(obj)</code> to iterate over all objects and keys. Use <code>hasOwnProperty()</code> and <code>Array.concat()</code> to append values for keys existing in multiple objects.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">merge</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>objs<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">[</span><span class="token operator">...</span>objs<span class="token punctuation">].</span><span class="token function">reduce</span><span class="token punctuation">(
|
||
(</span>acc<span class="token punctuation">,</span> obj<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> k<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
acc<span class="token punctuation">[</span>k<span class="token punctuation">]</span> <span class="token operator">=</span> acc<span class="token punctuation">.</span><span class="token function">hasOwnProperty</span><span class="token punctuation">(</span>k<span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token punctuation">[].</span><span class="token function">concat</span><span class="token punctuation">(</span>acc<span class="token punctuation">[</span>k<span class="token punctuation">]).</span><span class="token function">concat</span><span class="token punctuation">(</span>obj<span class="token punctuation">[</span>k<span class="token punctuation">]) :</span> obj<span class="token punctuation">[</span>k<span class="token punctuation">];</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
}, {}),
|
||
{}
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> object <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
a<span class="token punctuation">: [{</span> x<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> y<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}],</span>
|
||
b<span class="token punctuation">:</span> <span class="token number">1</span>
|
||
<span class="token punctuation">};</span>
|
||
<span class="token keyword">const</span> other <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
a<span class="token punctuation">: {</span> z<span class="token punctuation">:</span> <span class="token number">3</span> <span class="token punctuation">},</span>
|
||
b<span class="token punctuation">: [</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">],</span>
|
||
c<span class="token punctuation">:</span> <span class="token string">'foo'</span>
|
||
<span class="token punctuation">};</span>
|
||
<span class="token function">merge</span><span class="token punctuation">(</span>object<span class="token punctuation">,</span> other<span class="token punctuation">);</span> <span class="token comment">// { a: [ { x: 2 }, { y: 4 }, { z: 3 } ], b: [ 1, 2, 3 ], c: 'foo' }</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="objectfrompairs" class="section double-padded">objectFromPairs</h3><div class="section double-padded"><p>Creates an object from the given key-value pairs.</p><p>Use <code>Array.reduce()</code> to create and combine key-value pairs.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">objectFromPairs</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">((</span>a<span class="token punctuation">[</span>v<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]]</span> <span class="token operator">=</span> v<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]),</span> a<span class="token punctuation">), {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">objectFromPairs</span><span class="token punctuation">([[</span><span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">], [</span><span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]]);</span> <span class="token comment">// {a: 1, b: 2}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="objecttopairs" class="section double-padded">objectToPairs</h3><div class="section double-padded"><p>Creates an array of key-value pair arrays from an object.</p><p>Use <code>Object.keys()</code> and <code>Array.map()</code> to iterate over the object's keys and produce an array with key-value pairs.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">objectToPairs</span> <span class="token operator">=</span> obj <span class="token operator">=></span> Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">map</span><span class="token punctuation">(</span>k <span class="token operator">=></span> <span class="token punctuation">[</span>k<span class="token punctuation">,</span> obj<span class="token punctuation">[</span>k<span class="token punctuation">]]);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">objectToPairs</span><span class="token punctuation">({</span> a<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">});</span> <span class="token comment">// [['a',1],['b',2]]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="orderby" class="section double-padded">orderBy</h3><div class="section double-padded"><p>Returns a sorted array of objects ordered by properties and orders.</p><p>Uses <code>Array.sort()</code>, <code>Array.reduce()</code> on the <code>props</code> array with a default value of <code>0</code>, use array destructuring to swap the properties position depending on the order passed. If no <code>orders</code> array is passed it sort by <code>'asc'</code> by default.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">orderBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> props<span class="token punctuation">,</span> orders<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">sort</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
props<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> prop<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>acc <span class="token operator">===</span> <span class="token number">0</span><span class="token punctuation">) {</span>
|
||
<span class="token keyword">const</span> <span class="token punctuation">[</span>p1<span class="token punctuation">,</span> p2<span class="token punctuation">]</span> <span class="token operator">=</span> orders <span class="token operator">&&</span> orders<span class="token punctuation">[</span>i<span class="token punctuation">]</span> <span class="token operator">===</span> <span class="token string">'desc'</span> <span class="token operator">?</span> <span class="token punctuation">[</span>b<span class="token punctuation">[</span>prop<span class="token punctuation">],</span> a<span class="token punctuation">[</span>prop<span class="token punctuation">]] : [</span>a<span class="token punctuation">[</span>prop<span class="token punctuation">],</span> b<span class="token punctuation">[</span>prop<span class="token punctuation">]];</span>
|
||
acc <span class="token operator">=</span> p1 <span class="token operator">></span> p2 <span class="token operator">?</span> <span class="token number">1</span> <span class="token punctuation">:</span> p1 <span class="token operator"><</span> p2 <span class="token operator">? -</span><span class="token number">1</span> <span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">;
|
||
}</span>
|
||
<span class="token keyword">return</span> acc<span class="token punctuation">;
|
||
},</span> <span class="token number">0</span><span class="token punctuation">)
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> users <span class="token operator">=</span> <span class="token punctuation">[{</span> name<span class="token punctuation">:</span> <span class="token string">'fred'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">48</span> <span class="token punctuation">}, {</span> name<span class="token punctuation">:</span> <span class="token string">'barney'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">36</span> <span class="token punctuation">}, {</span> name<span class="token punctuation">:</span> <span class="token string">'fred'</span><span class="token punctuation">,</span> age<span class="token punctuation">:</span> <span class="token number">40</span> <span class="token punctuation">}];</span>
|
||
<span class="token function">orderBy</span><span class="token punctuation">(</span>users<span class="token punctuation">, [</span><span class="token string">'name'</span><span class="token punctuation">,</span> <span class="token string">'age'</span><span class="token punctuation">], [</span><span class="token string">'asc'</span><span class="token punctuation">,</span> <span class="token string">'desc'</span><span class="token punctuation">]);</span> <span class="token comment">// [{name: 'barney', age: 36}, {name: 'fred', age: 48}, {name: 'fred', age: 40}]</span>
|
||
<span class="token function">orderBy</span><span class="token punctuation">(</span>users<span class="token punctuation">, [</span><span class="token string">'name'</span><span class="token punctuation">,</span> <span class="token string">'age'</span><span class="token punctuation">]);</span> <span class="token comment">// [{name: 'barney', age: 36}, {name: 'fred', age: 40}, {name: 'fred', age: 48}]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="select" class="section double-padded">select</h3><div class="section double-padded"><p>Retrieve a set of properties indicated by the given selectors from an object.</p><p>Use <code>Array.map()</code> for each selector, <code>String.split('.')</code> to split each selector and <code>Array.reduce()</code> to get the value indicated by it.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">select</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token keyword">from</span><span class="token punctuation">,</span> <span class="token operator">...</span>selectors<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">[</span><span class="token operator">...</span>selectors<span class="token punctuation">].</span><span class="token function">map</span><span class="token punctuation">(</span>s <span class="token operator">=></span> s<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">'.'</span><span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>prev<span class="token punctuation">,</span> cur<span class="token punctuation">)</span> <span class="token operator">=></span> prev <span class="token operator">&&</span> prev<span class="token punctuation">[</span>cur<span class="token punctuation">],</span> <span class="token keyword">from</span><span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span> selector<span class="token punctuation">: {</span> to<span class="token punctuation">: {</span> val<span class="token punctuation">:</span> <span class="token string">'val to select'</span> <span class="token punctuation">} } };</span>
|
||
<span class="token function">select</span><span class="token punctuation">(</span>obj<span class="token punctuation">,</span> <span class="token string">'selector.to.val'</span><span class="token punctuation">);</span> <span class="token comment">// ['val to select']</span>
|
||
<span class="token function">select</span><span class="token punctuation">(</span>obj<span class="token punctuation">,</span> <span class="token string">'selector.to.val'</span><span class="token punctuation">,</span> <span class="token string">'selector.to'</span><span class="token punctuation">);</span> <span class="token comment">// ['val to select', { val: 'val to select' }]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="shallowclone" class="section double-padded">shallowClone</h3><div class="section double-padded"><p>Creates a shallow clone of an object.</p><p>Use <code>Object.assign()</code> and an empty object (<code>{}</code>) to create a shallow clone of the original.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">shallowClone</span> <span class="token operator">=</span> obj <span class="token operator">=></span> Object<span class="token punctuation">.</span><span class="token function">assign</span><span class="token punctuation">({},</span> obj<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> a <span class="token operator">=</span> <span class="token punctuation">{</span> x<span class="token punctuation">:</span> <span class="token boolean">true</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">};</span>
|
||
<span class="token keyword">const</span> b <span class="token operator">=</span> <span class="token function">shallowClone</span><span class="token punctuation">(</span>a<span class="token punctuation">);</span> <span class="token comment">// a !== b</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="size" class="section double-padded">size</h3><div class="section double-padded"><p>Get size of arrays, objects or strings.</p><p>Get type of <code>val</code> (<code>array</code>, <code>object</code> or <code>string</code>). Use <code>length</code> property for arrays. Use <code>length</code> or <code>size</code> value if available or number of keys for objects. Use <code>size</code> of a <a href="https://developer.mozilla.org/en-US/docs/Web/API/Blob"><code>Blob</code> object</a> created from <code>val</code> for strings.</p><p>Split strings into array of characters with <code>split('')</code> and return its length.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">size</span> <span class="token operator">=</span> val <span class="token operator">=></span>
|
||
Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>val<span class="token punctuation">)</span>
|
||
<span class="token operator">?</span> val<span class="token punctuation">.</span>length
|
||
<span class="token punctuation">:</span> val <span class="token operator">&&</span> <span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'object'</span>
|
||
<span class="token operator">?</span> val<span class="token punctuation">.</span>size <span class="token operator">||</span> val<span class="token punctuation">.</span>length <span class="token operator">||</span> Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>val<span class="token punctuation">).</span>length
|
||
<span class="token punctuation">:</span> <span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'string'</span> <span class="token operator">?</span> <span class="token keyword">new</span> <span class="token class-name">Blob</span><span class="token punctuation">([</span>val<span class="token punctuation">]).</span>size <span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">size</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// 5</span>
|
||
<span class="token function">size</span><span class="token punctuation">(</span><span class="token string">'size'</span><span class="token punctuation">);</span> <span class="token comment">// 4</span>
|
||
<span class="token function">size</span><span class="token punctuation">({</span> one<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> two<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span> three<span class="token punctuation">:</span> <span class="token number">3</span> <span class="token punctuation">});</span> <span class="token comment">// 3</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="transform" class="section double-padded">transform</h3><div class="section double-padded"><p>Applies a function against an accumulator and each key in the object (from left to right).</p><p>Use <code>Object.keys(obj)</code> to iterate over each key in the object, <code>Array.reduce()</code> to call the apply the specified function against the given accumulator.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">transform</span> <span class="token operator">=</span> <span class="token punctuation">(</span>obj<span class="token punctuation">,</span> fn<span class="token punctuation">,</span> acc<span class="token punctuation">)</span> <span class="token operator">=></span> Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">).</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> k<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">fn</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> obj<span class="token punctuation">[</span>k<span class="token punctuation">],</span> k<span class="token punctuation">,</span> obj<span class="token punctuation">),</span> acc<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">transform</span><span class="token punctuation">(
|
||
{</span> a<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span> c<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">},
|
||
(</span>r<span class="token punctuation">,</span> v<span class="token punctuation">,</span> k<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{
|
||
(</span>r<span class="token punctuation">[</span>v<span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token punctuation">(</span>r<span class="token punctuation">[</span>v<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[])).</span><span class="token function">push</span><span class="token punctuation">(</span>k<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> r<span class="token punctuation">;
|
||
},
|
||
{}
|
||
);</span> <span class="token comment">// { '1': ['a', 'c'], '2': ['b'] }</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="truthcheckcollection" class="section double-padded">truthCheckCollection</h3><div class="section double-padded"><p>Checks if the predicate (second argument) is truthy on all elements of a collection (first argument).</p><p>Use <code>Array.every()</code> to check if each passed object has the specified property and if it returns a truthy value.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">truthCheckCollection</span> <span class="token operator">=</span> <span class="token punctuation">(</span>collection<span class="token punctuation">,</span> pre<span class="token punctuation">)</span> <span class="token operator">=></span> collection<span class="token punctuation">.</span><span class="token function">every</span><span class="token punctuation">(</span>obj <span class="token operator">=></span> obj<span class="token punctuation">[</span>pre<span class="token punctuation">]);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">truthCheckCollection</span><span class="token punctuation">([{</span> user<span class="token punctuation">:</span> <span class="token string">'Tinky-Winky'</span><span class="token punctuation">,</span> sex<span class="token punctuation">:</span> <span class="token string">'male'</span> <span class="token punctuation">}, {</span> user<span class="token punctuation">:</span> <span class="token string">'Dipsy'</span><span class="token punctuation">,</span> sex<span class="token punctuation">:</span> <span class="token string">'male'</span> <span class="token punctuation">}],</span> <span class="token string">'sex'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">String</h2><div class="card fluid"><h3 id="anagrams" class="section double-padded">anagrams</h3><div class="section double-padded"><p>⚠️ <strong>WARNING</strong>: This function's execution time increases exponentially with each character. Anything more than 8 to 10 characters will cause your browser to hang as it tries to solve all the different combinations.</p><p>Generates all anagrams of a string (contains duplicates).</p><p>Use recursion. For each letter in the given string, create all the partial anagrams for the rest of its letters. Use <code>Array.map()</code> to combine the letter with each partial anagram, then <code>Array.reduce()</code> to combine all anagrams in one array. Base cases are for string <code>length</code> equal to <code>2</code> or <code>1</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">anagrams</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>str<span class="token punctuation">.</span>length <span class="token operator"><=</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token keyword">return</span> str<span class="token punctuation">.</span>length <span class="token operator">===</span> <span class="token number">2</span> <span class="token operator">?</span> <span class="token punctuation">[</span>str<span class="token punctuation">,</span> str<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">+</span> str<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]] : [</span>str<span class="token punctuation">];</span>
|
||
<span class="token keyword">return</span> str
|
||
<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">)
|
||
.</span><span class="token function">reduce</span><span class="token punctuation">(
|
||
(</span>acc<span class="token punctuation">,</span> letter<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
acc<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span><span class="token function">anagrams</span><span class="token punctuation">(</span>str<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">+</span> str<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">)).</span><span class="token function">map</span><span class="token punctuation">(</span>val <span class="token operator">=></span> letter <span class="token operator">+</span> val<span class="token punctuation">)),
|
||
[]
|
||
);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">anagrams</span><span class="token punctuation">(</span><span class="token string">'abc'</span><span class="token punctuation">);</span> <span class="token comment">// ['abc','acb','bac','bca','cab','cba']</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="bytesize" class="section double-padded">byteSize</h3><div class="section double-padded"><p>Returns the length of a string in bytes.</p><p>Convert a given string to a <a href="https://developer.mozilla.org/en-US/docs/Web/API/Blob"><code>Blob</code> Object</a> and find its <code>size</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">byteSize</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token keyword">new</span> <span class="token class-name">Blob</span><span class="token punctuation">([</span>str<span class="token punctuation">]).</span>size<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">byteSize</span><span class="token punctuation">(</span><span class="token string">'😀'</span><span class="token punctuation">);</span> <span class="token comment">// 4</span>
|
||
<span class="token function">byteSize</span><span class="token punctuation">(</span><span class="token string">'Hello World'</span><span class="token punctuation">);</span> <span class="token comment">// 11</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="capitalize" class="section double-padded">capitalize</h3><div class="section double-padded"><p>Capitalizes the first letter of a string.</p><p>Use array destructuring and <code>String.toUpperCase()</code> to capitalize first letter, <code>...rest</code> to get array of characters after first letter and then <code>Array.join('')</code> to make it a string again. Omit the <code>lowerRest</code> parameter to keep the rest of the string intact, or set it to <code>true</code> to convert to lowercase.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">capitalize</span> <span class="token operator">=</span> <span class="token punctuation">([</span>first<span class="token punctuation">,</span> <span class="token operator">...</span>rest<span class="token punctuation">],</span> lowerRest <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
first<span class="token punctuation">.</span><span class="token function">toUpperCase</span><span class="token punctuation">()</span> <span class="token operator">+</span> <span class="token punctuation">(</span>lowerRest <span class="token operator">?</span> rest<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">).</span><span class="token function">toLowerCase</span><span class="token punctuation">() :</span> rest<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">capitalize</span><span class="token punctuation">(</span><span class="token string">'fooBar'</span><span class="token punctuation">);</span> <span class="token comment">// 'FooBar'</span>
|
||
<span class="token function">capitalize</span><span class="token punctuation">(</span><span class="token string">'fooBar'</span><span class="token punctuation">,</span> <span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// 'Foobar'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="capitalizeeveryword" class="section double-padded">capitalizeEveryWord</h3><div class="section double-padded"><p>Capitalizes the first letter of every word in a string.</p><p>Use <code>String.replace()</code> to match the first character of each word and <code>String.toUpperCase()</code> to capitalize it.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">capitalizeEveryWord</span> <span class="token operator">=</span> str <span class="token operator">=></span> str<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/\b[a-z]/g</span><span class="token punctuation">,</span> char <span class="token operator">=></span> char<span class="token punctuation">.</span><span class="token function">toUpperCase</span><span class="token punctuation">());</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">capitalizeEveryWord</span><span class="token punctuation">(</span><span class="token string">'hello world!'</span><span class="token punctuation">);</span> <span class="token comment">// 'Hello World!'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="decapitalize" class="section double-padded">decapitalize</h3><div class="section double-padded"><p>Decapitalizes the first letter of a string.</p><p>Use array destructuring and <code>String.toLowerCase()</code> to decapitalize first letter, <code>...rest</code> to get array of characters after first letter and then <code>Array.join('')</code> to make it a string again. Omit the <code>upperRest</code> parameter to keep the rest of the string intact, or set it to <code>true</code> to convert to uppercase.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">decapitalize</span> <span class="token operator">=</span> <span class="token punctuation">([</span>first<span class="token punctuation">,</span> <span class="token operator">...</span>rest<span class="token punctuation">],</span> upperRest <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
first<span class="token punctuation">.</span><span class="token function">toLowerCase</span><span class="token punctuation">()</span> <span class="token operator">+</span> <span class="token punctuation">(</span>upperRest <span class="token operator">?</span> rest<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">).</span><span class="token function">toUpperCase</span><span class="token punctuation">() :</span> rest<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">decapitalize</span><span class="token punctuation">(</span><span class="token string">'FooBar'</span><span class="token punctuation">);</span> <span class="token comment">// 'fooBar'</span>
|
||
<span class="token function">decapitalize</span><span class="token punctuation">(</span><span class="token string">'FooBar'</span><span class="token punctuation">,</span> <span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// 'fOOBAR'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="escapehtml" class="section double-padded">escapeHTML</h3><div class="section double-padded"><p>Escapes a string for use in HTML.</p><p>Use <code>String.replace()</code> with a regexp that matches the characters that need to be escaped, using a callback function to replace each character instance with its associated escaped character using a dictionary (object).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">escapeHTML</span> <span class="token operator">=</span> str <span class="token operator">=></span>
|
||
str<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span>
|
||
<span class="token regex">/[&<>'"]/g</span><span class="token punctuation">,</span>
|
||
tag <span class="token operator">=></span>
|
||
<span class="token punctuation">({</span>
|
||
<span class="token string">'&'</span><span class="token punctuation">:</span> <span class="token string">'&amp;'</span><span class="token punctuation">,</span>
|
||
<span class="token string">'<'</span><span class="token punctuation">:</span> <span class="token string">'&lt;'</span><span class="token punctuation">,</span>
|
||
<span class="token string">'>'</span><span class="token punctuation">:</span> <span class="token string">'&gt;'</span><span class="token punctuation">,</span>
|
||
<span class="token string">"'"</span><span class="token punctuation">:</span> <span class="token string">'&#39;'</span><span class="token punctuation">,</span>
|
||
<span class="token string">'"'</span><span class="token punctuation">:</span> <span class="token string">'&quot;'</span>
|
||
<span class="token punctuation">}[</span>tag<span class="token punctuation">]</span> <span class="token operator">||</span> tag<span class="token punctuation">)
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">escapeHTML</span><span class="token punctuation">(</span><span class="token string">'<a href="#">Me & you</a>'</span><span class="token punctuation">);</span> <span class="token comment">// '&lt;a href=&quot;#&quot;&gt;Me &amp; you&lt;/a&gt;'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="escaperegexp" class="section double-padded">escapeRegExp</h3><div class="section double-padded"><p>Escapes a string to use in a regular expression.</p><p>Use <code>String.replace()</code> to escape special characters.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">escapeRegExp</span> <span class="token operator">=</span> str <span class="token operator">=></span> str<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/[.*+?^${}()|[\]\\]/g</span><span class="token punctuation">,</span> <span class="token string">'\\$&'</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">escapeRegExp</span><span class="token punctuation">(</span><span class="token string">'(test)'</span><span class="token punctuation">);</span> <span class="token comment">// \\(test\\)</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="fromcamelcase" class="section double-padded">fromCamelCase</h3><div class="section double-padded"><p>Converts a string from camelcase.</p><p>Use <code>String.replace()</code> to remove underscores, hyphens, and spaces and convert words to camelcase. Omit the second argument to use a default <code>separator</code> of <code>_</code>.</p><pre class="language-js"><span class="token keyword">const</span> fromCamelCase <span class="token operator">=</span> <span class="token punctuation">(</span>str<span class="token punctuation">,</span> separator <span class="token operator">=</span> <span class="token string">'_'</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
str
|
||
<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/([a-z\d])([A-Z])/g</span><span class="token punctuation">,</span> <span class="token string">'$1'</span> <span class="token operator">+</span> separator <span class="token operator">+</span> <span class="token string">'$2'</span><span class="token punctuation">)
|
||
.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/([A-Z]+)([A-Z][a-z\d]+)/g</span><span class="token punctuation">,</span> <span class="token string">'$1'</span> <span class="token operator">+</span> separator <span class="token operator">+</span> <span class="token string">'$2'</span><span class="token punctuation">)
|
||
.</span><span class="token function">toLowerCase</span><span class="token punctuation">();</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">fromCamelCase</span><span class="token punctuation">(</span><span class="token string">'someDatabaseFieldName'</span><span class="token punctuation">,</span> <span class="token string">' '</span><span class="token punctuation">);</span> <span class="token comment">// 'some database field name'</span>
|
||
<span class="token function">fromCamelCase</span><span class="token punctuation">(</span><span class="token string">'someLabelThatNeedsToBeCamelized'</span><span class="token punctuation">,</span> <span class="token string">'-'</span><span class="token punctuation">);</span> <span class="token comment">// 'some-label-that-needs-to-be-camelized'</span>
|
||
<span class="token function">fromCamelCase</span><span class="token punctuation">(</span><span class="token string">'someJavascriptProperty'</span><span class="token punctuation">,</span> <span class="token string">'_'</span><span class="token punctuation">);</span> <span class="token comment">// 'some_javascript_property'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isabsoluteurl" class="section double-padded">isAbsoluteURL</h3><div class="section double-padded"><p>Returns <code>true</code> if the given string is an absolute URL, <code>false</code> otherwise.</p><p>Use a regular expression to test if the string is an absolute URL.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isAbsoluteURL</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token regex">/^[a-z][a-z0-9+.-]*:/</span><span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>str<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isAbsoluteURL</span><span class="token punctuation">(</span><span class="token string">'https://google.com'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isAbsoluteURL</span><span class="token punctuation">(</span><span class="token string">'ftp://www.myserver.net'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isAbsoluteURL</span><span class="token punctuation">(</span><span class="token string">'/foo/bar'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="islowercase" class="section double-padded">isLowerCase</h3><div class="section double-padded"><p>Checks if a string is lower case.</p><p>Convert the given string to lower case, using <code>String.toLowerCase()</code> and compare it to the original.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isLowerCase</span> <span class="token operator">=</span> str <span class="token operator">=></span> str <span class="token operator">===</span> str<span class="token punctuation">.</span><span class="token function">toLowerCase</span><span class="token punctuation">();</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isLowerCase</span><span class="token punctuation">(</span><span class="token string">'abc'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isLowerCase</span><span class="token punctuation">(</span><span class="token string">'a3@$'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isLowerCase</span><span class="token punctuation">(</span><span class="token string">'Ab4'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isuppercase" class="section double-padded">isUpperCase</h3><div class="section double-padded"><p>Checks if a string is upper case.</p><p>Convert the given string to upper case, using <code>String.toUpperCase()</code> and compare it to the original.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isUpperCase</span> <span class="token operator">=</span> str <span class="token operator">=></span> str <span class="token operator">===</span> str<span class="token punctuation">.</span><span class="token function">toUpperCase</span><span class="token punctuation">();</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isUpperCase</span><span class="token punctuation">(</span><span class="token string">'ABC'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isLowerCase</span><span class="token punctuation">(</span><span class="token string">'A3@$'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isLowerCase</span><span class="token punctuation">(</span><span class="token string">'aB4'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="mask" class="section double-padded">mask</h3><div class="section double-padded"><p>Replaces all but the last <code>num</code> of characters with the specified mask character.</p><p>Use <code>String.slice()</code> to grab the portion of the characters that need to be masked and use <code>String.replace()</code> with a regexp to replace every character with the mask character. Concatenate the masked characters with the remaining unmasked portion of the string. Omit the second argument, <code>num</code>, to keep a default of <code>4</code> characters unmasked. If <code>num</code> is negative, the unmasked characters will be at the start of the string. Omit the third argument, <code>mask</code>, to use a default character of <code>'*'</code> for the mask.</p><pre class="language-js"><span class="token keyword">const</span> mask <span class="token operator">=</span> <span class="token punctuation">(</span>cc<span class="token punctuation">,</span> num <span class="token operator">=</span> <span class="token number">4</span><span class="token punctuation">,</span> mask <span class="token operator">=</span> <span class="token string">'*'</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">(</span><span class="token string">''</span> <span class="token operator">+</span> cc<span class="token punctuation">).</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token operator">-</span>num<span class="token punctuation">).</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/./g</span><span class="token punctuation">,</span> mask<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token punctuation">(</span><span class="token string">''</span> <span class="token operator">+</span> cc<span class="token punctuation">).</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token operator">-</span>num<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">mask</span><span class="token punctuation">(</span><span class="token number">1234567890</span><span class="token punctuation">);</span> <span class="token comment">// '******7890'</span>
|
||
<span class="token function">mask</span><span class="token punctuation">(</span><span class="token number">1234567890</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">);</span> <span class="token comment">// '*******890'</span>
|
||
<span class="token function">mask</span><span class="token punctuation">(</span><span class="token number">1234567890</span><span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token string">'$'</span><span class="token punctuation">);</span> <span class="token comment">// '$$$$567890'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="palindrome" class="section double-padded">palindrome</h3><div class="section double-padded"><p>Returns <code>true</code> if the given string is a palindrome, <code>false</code> otherwise.</p><p>Convert string <code>String.toLowerCase()</code> and use <code>String.replace()</code> to remove non-alphanumeric characters from it. Then, <code>String.split('')</code> into individual characters, <code>Array.reverse()</code>, <code>String.join('')</code> and compare to the original, unreversed string, after converting it <code>String.tolowerCase()</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">palindrome</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> s <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">toLowerCase</span><span class="token punctuation">().</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex">/[\W_]/g</span><span class="token punctuation">,</span> <span class="token string">''</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
||
s <span class="token operator">===</span>
|
||
s
|
||
<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">)
|
||
.</span><span class="token function">reverse</span><span class="token punctuation">()
|
||
.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">)
|
||
);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">palindrome</span><span class="token punctuation">(</span><span class="token string">'taco cat'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="pluralize" class="section double-padded">pluralize</h3><div class="section double-padded"><p>Returns the singular or plural form of the word based on the input number. If the first argument is an <code>object</code>, it will use a closure by returning a function that can auto-pluralize words that don't simply end in <code>s</code> if the supplied dictionary contains the word.</p><p>If <code>num</code> is either <code>-1</code> or <code>1</code>, return the singular form of the word. If <code>num</code> is any other number, return the plural form. Omit the third argument to use the default of the singular word + <code>s</code>, or supply a custom pluralized word when necessary. If the first argument is an <code>object</code>, utilize a closure by returning a function which can use the supplied dictionary to resolve the correct plural form of the word.</p><pre class="language-js"><span class="token keyword">const</span> pluralize <span class="token operator">=</span> <span class="token punctuation">(</span>val<span class="token punctuation">,</span> word<span class="token punctuation">,</span> plural <span class="token operator">=</span> word <span class="token operator">+</span> <span class="token string">'s'</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> _pluralize <span class="token operator">=</span> <span class="token punctuation">(</span>num<span class="token punctuation">,</span> word<span class="token punctuation">,</span> plural <span class="token operator">=</span> word <span class="token operator">+</span> <span class="token string">'s'</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">].</span><span class="token function">includes</span><span class="token punctuation">(</span><span class="token function">Number</span><span class="token punctuation">(</span>num<span class="token punctuation">))</span> <span class="token operator">?</span> word <span class="token punctuation">:</span> plural<span class="token punctuation">;</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'object'</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token punctuation">(</span>num<span class="token punctuation">,</span> word<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">_pluralize</span><span class="token punctuation">(</span>num<span class="token punctuation">,</span> word<span class="token punctuation">,</span> val<span class="token punctuation">[</span>word<span class="token punctuation">]);</span>
|
||
<span class="token keyword">return</span> <span class="token function">_pluralize</span><span class="token punctuation">(</span>val<span class="token punctuation">,</span> word<span class="token punctuation">,</span> plural<span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">pluralize</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token string">'apple'</span><span class="token punctuation">);</span> <span class="token comment">// 'apples'</span>
|
||
<span class="token function">pluralize</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token string">'apple'</span><span class="token punctuation">);</span> <span class="token comment">// 'apple'</span>
|
||
<span class="token function">pluralize</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token string">'apple'</span><span class="token punctuation">);</span> <span class="token comment">// 'apples'</span>
|
||
<span class="token function">pluralize</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token string">'person'</span><span class="token punctuation">,</span> <span class="token string">'people'</span><span class="token punctuation">);</span> <span class="token comment">// 'people'</span>
|
||
|
||
<span class="token keyword">const</span> PLURALS <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
person<span class="token punctuation">:</span> <span class="token string">'people'</span><span class="token punctuation">,</span>
|
||
radius<span class="token punctuation">:</span> <span class="token string">'radii'</span>
|
||
<span class="token punctuation">};</span>
|
||
<span class="token keyword">const</span> autoPluralize <span class="token operator">=</span> <span class="token function">pluralize</span><span class="token punctuation">(</span>PLURALS<span class="token punctuation">);</span>
|
||
<span class="token function">autoPluralize</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token string">'person'</span><span class="token punctuation">);</span> <span class="token comment">// 'people'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="reversestring" class="section double-padded">reverseString</h3><div class="section double-padded"><p>Reverses a string.</p><p>Use the spread operator (<code>...</code>) and <code>Array.reverse()</code> to reverse the order of the characters in the string. Combine characters to get a string using <code>String.join('')</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">reverseString</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>str<span class="token punctuation">].</span><span class="token function">reverse</span><span class="token punctuation">().</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">reverseString</span><span class="token punctuation">(</span><span class="token string">'foobar'</span><span class="token punctuation">);</span> <span class="token comment">// 'raboof'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="sortcharactersinstring" class="section double-padded">sortCharactersInString</h3><div class="section double-padded"><p>Alphabetically sorts the characters in a string.</p><p>Use the spread operator (<code>...</code>), <code>Array.sort()</code> and <code>String.localeCompare()</code> to sort the characters in <code>str</code>, recombine using <code>String.join('')</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">sortCharactersInString</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>str<span class="token punctuation">].</span><span class="token function">sort</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> a<span class="token punctuation">.</span><span class="token function">localeCompare</span><span class="token punctuation">(</span>b<span class="token punctuation">)).</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">sortCharactersInString</span><span class="token punctuation">(</span><span class="token string">'cabbage'</span><span class="token punctuation">);</span> <span class="token comment">// 'aabbceg'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="splitlines" class="section double-padded">splitLines</h3><div class="section double-padded"><p>Splits a multiline string into an array of lines.</p><p>Use <code>String.split()</code> and a regular expression to match line breaks and create an array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">splitLines</span> <span class="token operator">=</span> str <span class="token operator">=></span> str<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token regex">/\r?\n/</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">splitLines</span><span class="token punctuation">(</span><span class="token string">'This\nis a\nmultiline\nstring.\n'</span><span class="token punctuation">);</span> <span class="token comment">// ['This', 'is a', 'multiline', 'string.' , '']</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="tocamelcase" class="section double-padded">toCamelCase</h3><div class="section double-padded"><p>Converts a string to camelcase.</p><p>Break the string into words and combine them capitalizing the first letter of each word, using a regexp.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">toCamelCase</span> <span class="token operator">=</span> str <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> s <span class="token operator">=</span>
|
||
str <span class="token operator">&&</span>
|
||
str
|
||
<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex">/[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+/g</span><span class="token punctuation">)
|
||
.</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> x<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">).</span><span class="token function">toUpperCase</span><span class="token punctuation">()</span> <span class="token operator">+</span> x<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">).</span><span class="token function">toLowerCase</span><span class="token punctuation">())
|
||
.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> s<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">).</span><span class="token function">toLowerCase</span><span class="token punctuation">()</span> <span class="token operator">+</span> s<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">toCamelCase</span><span class="token punctuation">(</span><span class="token string">'some_database_field_name'</span><span class="token punctuation">);</span> <span class="token comment">// 'someDatabaseFieldName'</span>
|
||
<span class="token function">toCamelCase</span><span class="token punctuation">(</span><span class="token string">'Some label that needs to be camelized'</span><span class="token punctuation">);</span> <span class="token comment">// 'someLabelThatNeedsToBeCamelized'</span>
|
||
<span class="token function">toCamelCase</span><span class="token punctuation">(</span><span class="token string">'some-javascript-property'</span><span class="token punctuation">);</span> <span class="token comment">// 'someJavascriptProperty'</span>
|
||
<span class="token function">toCamelCase</span><span class="token punctuation">(</span><span class="token string">'some-mixed_string with spaces_underscores-and-hyphens'</span><span class="token punctuation">);</span> <span class="token comment">// 'someMixedStringWithSpacesUnderscoresAndHyphens'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="tokebabcase" class="section double-padded">toKebabCase</h3><div class="section double-padded"><p>Converts a string to kebab case.</p><p>Break the string into words and combine them adding <code>-</code> as a separator, using a regexp.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">toKebabCase</span> <span class="token operator">=</span> str <span class="token operator">=></span>
|
||
str <span class="token operator">&&</span>
|
||
str
|
||
<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex">/[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+/g</span><span class="token punctuation">)
|
||
.</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> x<span class="token punctuation">.</span><span class="token function">toLowerCase</span><span class="token punctuation">())
|
||
.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">'-'</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">toKebabCase</span><span class="token punctuation">(</span><span class="token string">'camelCase'</span><span class="token punctuation">);</span> <span class="token comment">// 'camel-case'</span>
|
||
<span class="token function">toKebabCase</span><span class="token punctuation">(</span><span class="token string">'some text'</span><span class="token punctuation">);</span> <span class="token comment">// 'some-text'</span>
|
||
<span class="token function">toKebabCase</span><span class="token punctuation">(</span><span class="token string">'some-mixed_string With spaces_underscores-and-hyphens'</span><span class="token punctuation">);</span> <span class="token comment">// 'some-mixed-string-with-spaces-underscores-and-hyphens'</span>
|
||
<span class="token function">toKebabCase</span><span class="token punctuation">(</span><span class="token string">'AllThe-small Things'</span><span class="token punctuation">);</span> <span class="token comment">// "all-the-small-things"</span>
|
||
<span class="token function">toKebabCase</span><span class="token punctuation">(</span><span class="token string">'IAmListeningToFMWhileLoadingDifferentURLOnMyBrowserAndAlsoEditingSomeXMLAndHTML'</span><span class="token punctuation">);</span> <span class="token comment">// "i-am-listening-to-fm-while-loading-different-url-on-my-browser-and-also-editing-xml-and-html"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="tosnakecase" class="section double-padded">toSnakeCase</h3><div class="section double-padded"><p>Converts a string to snake case.</p><p>Break the string into words and combine them adding <code>_</code> as a separator, using a regexp.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">toSnakeCase</span> <span class="token operator">=</span> str <span class="token operator">=></span>
|
||
str <span class="token operator">&&</span>
|
||
str
|
||
<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex">/[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+/g</span><span class="token punctuation">)
|
||
.</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> x<span class="token punctuation">.</span><span class="token function">toLowerCase</span><span class="token punctuation">())
|
||
.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">'_'</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">toSnakeCase</span><span class="token punctuation">(</span><span class="token string">'camelCase'</span><span class="token punctuation">);</span> <span class="token comment">// 'camel_case'</span>
|
||
<span class="token function">toSnakeCase</span><span class="token punctuation">(</span><span class="token string">'some text'</span><span class="token punctuation">);</span> <span class="token comment">// 'some_text'</span>
|
||
<span class="token function">toSnakeCase</span><span class="token punctuation">(</span><span class="token string">'some-mixed_string With spaces_underscores-and-hyphens'</span><span class="token punctuation">);</span> <span class="token comment">// 'some_mixed_string_with_spaces_underscores_and_hyphens'</span>
|
||
<span class="token function">toSnakeCase</span><span class="token punctuation">(</span><span class="token string">'AllThe-small Things'</span><span class="token punctuation">);</span> <span class="token comment">// "all_the_smal_things"</span>
|
||
<span class="token function">toSnakeCase</span><span class="token punctuation">(</span><span class="token string">'IAmListeningToFMWhileLoadingDifferentURLOnMyBrowserAndAlsoEditingSomeXMLAndHTML'</span><span class="token punctuation">);</span> <span class="token comment">// "i_am_listening_to_fm_while_loading_different_url_on_my_browser_and_also_editing_some_xml_and_html"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="truncatestring" class="section double-padded">truncateString</h3><div class="section double-padded"><p>Truncates a string up to a specified length.</p><p>Determine if the string's <code>length</code> is greater than <code>num</code>. Return the string truncated to the desired length, with <code>'...'</code> appended to the end or the original string.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">truncateString</span> <span class="token operator">=</span> <span class="token punctuation">(</span>str<span class="token punctuation">,</span> num<span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
str<span class="token punctuation">.</span>length <span class="token operator">></span> num <span class="token operator">?</span> str<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> num <span class="token operator">></span> <span class="token number">3</span> <span class="token operator">?</span> num <span class="token operator">-</span> <span class="token number">3</span> <span class="token punctuation">:</span> num<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">'...'</span> <span class="token punctuation">:</span> str<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">truncateString</span><span class="token punctuation">(</span><span class="token string">'boomerang'</span><span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">);</span> <span class="token comment">// 'boom...'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="unescapehtml" class="section double-padded">unescapeHTML</h3><div class="section double-padded"><p>Unescapes escaped HTML characters.</p><p>Use <code>String.replace()</code> with a regex that matches the characters that need to be unescaped, using a callback function to replace each escaped character instance with its associated unescaped character using a dictionary (object).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">unescapeHTML</span> <span class="token operator">=</span> str <span class="token operator">=></span>
|
||
str<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span>
|
||
<span class="token regex">/&amp;|&lt;|&gt;|&#39;|&quot;/g</span><span class="token punctuation">,</span>
|
||
tag <span class="token operator">=></span>
|
||
<span class="token punctuation">({</span>
|
||
<span class="token string">'&amp;'</span><span class="token punctuation">:</span> <span class="token string">'&'</span><span class="token punctuation">,</span>
|
||
<span class="token string">'&lt;'</span><span class="token punctuation">:</span> <span class="token string">'<'</span><span class="token punctuation">,</span>
|
||
<span class="token string">'&gt;'</span><span class="token punctuation">:</span> <span class="token string">'>'</span><span class="token punctuation">,</span>
|
||
<span class="token string">'&#39;'</span><span class="token punctuation">:</span> <span class="token string">"'"</span><span class="token punctuation">,</span>
|
||
<span class="token string">'&quot;'</span><span class="token punctuation">:</span> <span class="token string">'"'</span>
|
||
<span class="token punctuation">}[</span>tag<span class="token punctuation">]</span> <span class="token operator">||</span> tag<span class="token punctuation">)
|
||
);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">unescapeHTML</span><span class="token punctuation">(</span><span class="token string">'&lt;a href=&quot;#&quot;&gt;Me &amp; you&lt;/a&gt;'</span><span class="token punctuation">);</span> <span class="token comment">// '<a href="#">Me & you</a>'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="words" class="section double-padded">words</h3><div class="section double-padded"><p>Converts a given string into an array of words.</p><p>Use <code>String.split()</code> with a supplied pattern (defaults to non-alpha as a regexp) to convert to an array of strings. Use <code>Array.filter()</code> to remove any empty strings. Omit the second argument to use the default regexp.</p><pre class="language-js"><span class="token keyword">const</span> words <span class="token operator">=</span> <span class="token punctuation">(</span>str<span class="token punctuation">,</span> pattern <span class="token operator">=</span> <span class="token regex">/[^a-zA-Z-]+/</span><span class="token punctuation">)</span> <span class="token operator">=></span> str<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span>pattern<span class="token punctuation">).</span><span class="token function">filter</span><span class="token punctuation">(</span>Boolean<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">words</span><span class="token punctuation">(</span><span class="token string">'I love javaScript!!'</span><span class="token punctuation">);</span> <span class="token comment">// ["I", "love", "javaScript"]</span>
|
||
<span class="token function">words</span><span class="token punctuation">(</span><span class="token string">'python, javaScript & coffee'</span><span class="token punctuation">);</span> <span class="token comment">// ["python", "javaScript", "coffee"]</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Type</h2><div class="card fluid"><h3 id="gettype" class="section double-padded">getType</h3><div class="section double-padded"><p>Returns the native type of a value.</p><p>Returns lowercased constructor name of value, <code>"undefined"</code> or <code>"null"</code> if value is <code>undefined</code> or <code>null</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">getType</span> <span class="token operator">=</span> v <span class="token operator">=></span>
|
||
v <span class="token operator">===</span> undefined <span class="token operator">?</span> <span class="token string">'undefined'</span> <span class="token punctuation">:</span> v <span class="token operator">===</span> <span class="token keyword">null</span> <span class="token operator">?</span> <span class="token string">'null'</span> <span class="token punctuation">:</span> v<span class="token punctuation">.</span>constructor<span class="token punctuation">.</span>name<span class="token punctuation">.</span><span class="token function">toLowerCase</span><span class="token punctuation">();</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">getType</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]));</span> <span class="token comment">// 'set'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isarray" class="section double-padded">isArray</h3><div class="section double-padded"><p>Checks if the given argument is an array.</p><p>Use <code>Array.isArray()</code> to check if a value is classified as an array.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isArray</span> <span class="token operator">=</span> val <span class="token operator">=></span> Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>val<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isArray</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">]);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isarraylike" class="section double-padded">isArrayLike</h3><div class="section double-padded"><p>Checks if the provided argument is array-like (i.e. is iterable).</p><p>Use the spread operator (<code>...</code>) to check if the provided argument is iterable inside a <code>try... catch</code> block and the comma operator (<code>,</code>) to return the appropriate value.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isArrayLike</span> <span class="token operator">=</span> val <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">try</span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token operator">...</span>val<span class="token punctuation">],</span> <span class="token boolean">true</span><span class="token punctuation">;
|
||
}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">e</span><span class="token punctuation">) {</span>
|
||
<span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;
|
||
}
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isArrayLike</span><span class="token punctuation">(</span>document<span class="token punctuation">.</span><span class="token function">querySelectorAll</span><span class="token punctuation">(</span><span class="token string">'.className'</span><span class="token punctuation">));</span> <span class="token comment">// true</span>
|
||
<span class="token function">isArrayLike</span><span class="token punctuation">(</span><span class="token string">'abc'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isArrayLike</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isboolean" class="section double-padded">isBoolean</h3><div class="section double-padded"><p>Checks if the given argument is a native boolean element.</p><p>Use <code>typeof</code> to check if a value is classified as a boolean primitive.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isBoolean</span> <span class="token operator">=</span> val <span class="token operator">=></span> <span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'boolean'</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isBoolean</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">isBoolean</span><span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isfunction" class="section double-padded">isFunction</h3><div class="section double-padded"><p>Checks if the given argument is a function.</p><p>Use <code>typeof</code> to check if a value is classified as a function primitive.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isFunction</span> <span class="token operator">=</span> val <span class="token operator">=></span> <span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'function'</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isFunction</span><span class="token punctuation">(</span><span class="token string">'x'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">isFunction</span><span class="token punctuation">(</span>x <span class="token operator">=></span> x<span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isnull" class="section double-padded">isNull</h3><div class="section double-padded"><p>Returns <code>true</code> if the specified value is <code>null</code>, <code>false</code> otherwise.</p><p>Use the strict equality operator to check if the value and of <code>val</code> are equal to <code>null</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isNull</span> <span class="token operator">=</span> val <span class="token operator">=></span> val <span class="token operator">===</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isNull</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isnumber" class="section double-padded">isNumber</h3><div class="section double-padded"><p>Checks if the given argument is a number.</p><p>Use <code>typeof</code> to check if a value is classified as a number primitive.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isNumber</span> <span class="token operator">=</span> val <span class="token operator">=></span> <span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'number'</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isNumber</span><span class="token punctuation">(</span><span class="token string">'1'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">isNumber</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isobject" class="section double-padded">isObject</h3><div class="section double-padded"><p>Returns a boolean determining if the passed value is an object or not.</p><p>Uses the <code>Object</code> constructor to create an object wrapper for the given value. If the value is <code>null</code> or <code>undefined</code>, create and return an empty object. Οtherwise, return an object of a type that corresponds to the given value.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isObject</span> <span class="token operator">=</span> obj <span class="token operator">=></span> obj <span class="token operator">===</span> <span class="token function">Object</span><span class="token punctuation">(</span>obj<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isObject</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isObject</span><span class="token punctuation">([]);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isObject</span><span class="token punctuation">([</span><span class="token string">'Hello!'</span><span class="token punctuation">]);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isObject</span><span class="token punctuation">({</span> a<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">});</span> <span class="token comment">// true</span>
|
||
<span class="token function">isObject</span><span class="token punctuation">({});</span> <span class="token comment">// true</span>
|
||
<span class="token function">isObject</span><span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isprimitive" class="section double-padded">isPrimitive</h3><div class="section double-padded"><p>Returns a boolean determining if the passed value is primitive or not.</p><p>Use <code>Array.includes()</code> on an array of type strings which are not primitive, supplying the type using <code>typeof</code>. Since <code>typeof null</code> evaluates to <code>'object'</code>, it needs to be directly compared.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isPrimitive</span> <span class="token operator">=</span> val <span class="token operator">=> !</span><span class="token punctuation">[</span><span class="token string">'object'</span><span class="token punctuation">,</span> <span class="token string">'function'</span><span class="token punctuation">].</span><span class="token function">includes</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> val<span class="token punctuation">)</span> <span class="token operator">||</span> val <span class="token operator">===</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isPrimitive</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isPrimitive</span><span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isPrimitive</span><span class="token punctuation">(</span><span class="token string">'Hello!'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isPrimitive</span><span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isPrimitive</span><span class="token punctuation">(</span><span class="token function">Symbol</span><span class="token punctuation">());</span> <span class="token comment">// true</span>
|
||
<span class="token function">isPrimitive</span><span class="token punctuation">([]);</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="ispromiselike" class="section double-padded">isPromiseLike</h3><div class="section double-padded"><p>Returns <code>true</code> if an object looks like a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise"><code>Promise</code></a>, <code>false</code> otherwise.</p><p>Check if the object is not <code>null</code>, its <code>typeof</code> matches either <code>object</code> or <code>function</code> and if it has a <code>.then</code> property, which is also a <code>function</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isPromiseLike</span> <span class="token operator">=</span> obj <span class="token operator">=></span>
|
||
obj <span class="token operator">!==</span> <span class="token keyword">null</span> <span class="token operator">&&</span>
|
||
<span class="token punctuation">(</span><span class="token keyword">typeof</span> obj <span class="token operator">===</span> <span class="token string">'object'</span> <span class="token operator">||</span> <span class="token keyword">typeof</span> obj <span class="token operator">===</span> <span class="token string">'function'</span><span class="token punctuation">)</span> <span class="token operator">&&</span>
|
||
<span class="token keyword">typeof</span> obj<span class="token punctuation">.</span>then <span class="token operator">===</span> <span class="token string">'function'</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isPromiseLike</span><span class="token punctuation">({</span>
|
||
then<span class="token punctuation">:</span> <span class="token keyword">function</span><span class="token punctuation">() {</span>
|
||
<span class="token keyword">return</span> <span class="token string">''</span><span class="token punctuation">;
|
||
}
|
||
});</span> <span class="token comment">// true</span>
|
||
<span class="token function">isPromiseLike</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">isPromiseLike</span><span class="token punctuation">({});</span> <span class="token comment">// false</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isstring" class="section double-padded">isString</h3><div class="section double-padded"><p>Checks if the given argument is a string.</p><p>Use <code>typeof</code> to check if a value is classified as a string primitive.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isString</span> <span class="token operator">=</span> val <span class="token operator">=></span> <span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'string'</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isString</span><span class="token punctuation">(</span><span class="token string">'10'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="issymbol" class="section double-padded">isSymbol</h3><div class="section double-padded"><p>Checks if the given argument is a symbol.</p><p>Use <code>typeof</code> to check if a value is classified as a symbol primitive.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isSymbol</span> <span class="token operator">=</span> val <span class="token operator">=></span> <span class="token keyword">typeof</span> val <span class="token operator">===</span> <span class="token string">'symbol'</span><span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isSymbol</span><span class="token punctuation">(</span><span class="token function">Symbol</span><span class="token punctuation">(</span><span class="token string">'x'</span><span class="token punctuation">));</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="isvalidjson" class="section double-padded">isValidJSON</h3><div class="section double-padded"><p>Checks if the provided argument is a valid JSON.</p><p>Use <code>JSON.parse()</code> and a <code>try... catch</code> block to check if the provided argument is a valid JSON.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">isValidJSON</span> <span class="token operator">=</span> obj <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">try</span> <span class="token punctuation">{</span>
|
||
JSON<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>obj<span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;
|
||
}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">e</span><span class="token punctuation">) {</span>
|
||
<span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;
|
||
}
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">isValidJSON</span><span class="token punctuation">(</span><span class="token string">'{"name":"Adam","age":20}'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">isValidJSON</span><span class="token punctuation">(</span><span class="token string">'{"name":"Adam",age:"20"}'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">isValidJSON</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><h2 style="text-align:center">Utility</h2><div class="card fluid"><h3 id="cloneregexp" class="section double-padded">cloneRegExp</h3><div class="section double-padded"><p>Clones a regular expression.</p><p>Use <code>new RegExp()</code>, <code>RegExp.source</code> and <code>RegExp.flags</code> to clone the given regular expression.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">cloneRegExp</span> <span class="token operator">=</span> regExp <span class="token operator">=></span> <span class="token keyword">new</span> <span class="token class-name">RegExp</span><span class="token punctuation">(</span>regExp<span class="token punctuation">.</span>source<span class="token punctuation">,</span> regExp<span class="token punctuation">.</span>flags<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> regExp <span class="token operator">=</span> <span class="token regex">/lorem ipsum/gi</span><span class="token punctuation">;</span>
|
||
<span class="token keyword">const</span> regExp2 <span class="token operator">=</span> <span class="token function">cloneRegExp</span><span class="token punctuation">(</span>regExp<span class="token punctuation">);</span> <span class="token comment">// /lorem ipsum/gi</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="coalesce" class="section double-padded">coalesce</h3><div class="section double-padded"><p>Returns the first non-null/undefined argument.</p><p>Use <code>Array.find()</code> to return the first non <code>null</code>/<code>undefined</code> argument.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">coalesce</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> args<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span>_ <span class="token operator">=> !</span><span class="token punctuation">[</span>undefined<span class="token punctuation">,</span> <span class="token keyword">null</span><span class="token punctuation">].</span><span class="token function">includes</span><span class="token punctuation">(</span>_<span class="token punctuation">));</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">coalesce</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">,</span> undefined<span class="token punctuation">,</span> <span class="token string">''</span><span class="token punctuation">,</span> <span class="token number">NaN</span><span class="token punctuation">,</span> <span class="token string">'Waldo'</span><span class="token punctuation">);</span> <span class="token comment">// ""</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="coalescefactory" class="section double-padded">coalesceFactory</h3><div class="section double-padded"><p>Returns a customized coalesce function that returns the first argument that returns <code>true</code> from the provided argument validation function.</p><p>Use <code>Array.find()</code> to return the first argument that returns <code>true</code> from the provided argument validation function.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">coalesceFactory</span> <span class="token operator">=</span> valid <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> args<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span>valid<span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> customCoalesce <span class="token operator">=</span> <span class="token function">coalesceFactory</span><span class="token punctuation">(</span>_ <span class="token operator">=> !</span><span class="token punctuation">[</span><span class="token keyword">null</span><span class="token punctuation">,</span> undefined<span class="token punctuation">,</span> <span class="token string">''</span><span class="token punctuation">,</span> <span class="token number">NaN</span><span class="token punctuation">].</span><span class="token function">includes</span><span class="token punctuation">(</span>_<span class="token punctuation">));</span>
|
||
<span class="token function">customCoalesce</span><span class="token punctuation">(</span>undefined<span class="token punctuation">,</span> <span class="token keyword">null</span><span class="token punctuation">,</span> <span class="token number">NaN</span><span class="token punctuation">,</span> <span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Waldo'</span><span class="token punctuation">);</span> <span class="token comment">// "Waldo"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="extendhex" class="section double-padded">extendHex</h3><div class="section double-padded"><p>Extends a 3-digit color code to a 6-digit color code.</p><p>Use <code>Array.map()</code>, <code>String.split()</code> and <code>Array.join()</code> to join the mapped array for converting a 3-digit RGB notated hexadecimal color-code to the 6-digit form. <code>Array.slice()</code> is used to remove <code>#</code> from string start since it's added once.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">extendHex</span> <span class="token operator">=</span> shortHex <span class="token operator">=></span>
|
||
<span class="token string">'#'</span> <span class="token operator">+</span>
|
||
shortHex
|
||
<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>shortHex<span class="token punctuation">.</span><span class="token function">startsWith</span><span class="token punctuation">(</span><span class="token string">'#'</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token number">1</span> <span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">)
|
||
.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">)
|
||
.</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> x <span class="token operator">+</span> x<span class="token punctuation">)
|
||
.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">extendHex</span><span class="token punctuation">(</span><span class="token string">'#03f'</span><span class="token punctuation">);</span> <span class="token comment">// '#0033ff'</span>
|
||
<span class="token function">extendHex</span><span class="token punctuation">(</span><span class="token string">'05a'</span><span class="token punctuation">);</span> <span class="token comment">// '#0055aa'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="geturlparameters" class="section double-padded">getURLParameters</h3><div class="section double-padded"><p>Returns an object containing the parameters of the current URL.</p><p>Use <code>String.match()</code> with an appropriate regular expression to get all key-value pairs, <code>Array.reduce()</code> to map and combine them into a single object. Pass <code>location.search</code> as the argument to apply to the current <code>url</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">getURLParameters</span> <span class="token operator">=</span> url <span class="token operator">=></span>
|
||
url
|
||
<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex">/([^?=&]+)(=([^&]*))/g</span><span class="token punctuation">)
|
||
.</span><span class="token function">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">((</span>a<span class="token punctuation">[</span>v<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> v<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span><span class="token string">'='</span><span class="token punctuation">))]</span> <span class="token operator">=</span> v<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>v<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span><span class="token string">'='</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">)),</span> a<span class="token punctuation">), {});</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">getURLParameters</span><span class="token punctuation">(</span><span class="token string">'http://url.com/page?name=Adam&surname=Smith'</span><span class="token punctuation">);</span> <span class="token comment">// {name: 'Adam', surname: 'Smith'}</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="hextorgb" class="section double-padded">hexToRGB<mark class="tag">advanced</mark></h3><div class="section double-padded"><p>Converts a color code to a <code>rgb()</code> or <code>rgba()</code> string if alpha value is provided.</p><p>Use bitwise right-shift operator and mask bits with <code>&</code> (and) operator to convert a hexadecimal color code (with or without prefixed with <code>#</code>) to a string with the RGB values. If it's 3-digit color code, first convert to 6-digit version. If an alpha value is provided alongside 6-digit hex, give <code>rgba()</code> string in return.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">hexToRGB</span> <span class="token operator">=</span> hex <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> alpha <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">,</span>
|
||
h <span class="token operator">=</span> hex<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>hex<span class="token punctuation">.</span><span class="token function">startsWith</span><span class="token punctuation">(</span><span class="token string">'#'</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token number">1</span> <span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>h<span class="token punctuation">.</span>length <span class="token operator">===</span> <span class="token number">3</span><span class="token punctuation">)</span> h <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">...</span>h<span class="token punctuation">].</span><span class="token function">map</span><span class="token punctuation">(</span>x <span class="token operator">=></span> x <span class="token operator">+</span> x<span class="token punctuation">).</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">else if</span> <span class="token punctuation">(</span>h<span class="token punctuation">.</span>length <span class="token operator">===</span> <span class="token number">8</span><span class="token punctuation">)</span> alpha <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
|
||
h <span class="token operator">=</span> <span class="token function">parseInt</span><span class="token punctuation">(</span>h<span class="token punctuation">,</span> <span class="token number">16</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
||
<span class="token string">'rgb'</span> <span class="token operator">+</span>
|
||
<span class="token punctuation">(</span>alpha <span class="token operator">?</span> <span class="token string">'a'</span> <span class="token punctuation">:</span> <span class="token string">''</span><span class="token punctuation">)</span> <span class="token operator">+</span>
|
||
<span class="token string">'('</span> <span class="token operator">+</span>
|
||
<span class="token punctuation">(</span>h <span class="token operator">>>></span> <span class="token punctuation">(</span>alpha <span class="token operator">?</span> <span class="token number">24</span> <span class="token punctuation">:</span> <span class="token number">16</span><span class="token punctuation">))</span> <span class="token operator">+</span>
|
||
<span class="token string">', '</span> <span class="token operator">+</span>
|
||
<span class="token punctuation">((</span>h <span class="token operator">&</span> <span class="token punctuation">(</span>alpha <span class="token operator">?</span> <span class="token number">0x00ff0000</span> <span class="token punctuation">:</span> <span class="token number">0x00ff00</span><span class="token punctuation">))</span> <span class="token operator">>>></span> <span class="token punctuation">(</span>alpha <span class="token operator">?</span> <span class="token number">16</span> <span class="token punctuation">:</span> <span class="token number">8</span><span class="token punctuation">))</span> <span class="token operator">+</span>
|
||
<span class="token string">', '</span> <span class="token operator">+</span>
|
||
<span class="token punctuation">((</span>h <span class="token operator">&</span> <span class="token punctuation">(</span>alpha <span class="token operator">?</span> <span class="token number">0x0000ff00</span> <span class="token punctuation">:</span> <span class="token number">0x0000ff</span><span class="token punctuation">))</span> <span class="token operator">>>></span> <span class="token punctuation">(</span>alpha <span class="token operator">?</span> <span class="token number">8</span> <span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">))</span> <span class="token operator">+</span>
|
||
<span class="token punctuation">(</span>alpha <span class="token operator">?</span> <span class="token template-string"><span class="token string">`, </span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>h <span class="token operator">&</span> <span class="token number">0x000000ff</span><span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">`</span></span> <span class="token punctuation">:</span> <span class="token string">''</span><span class="token punctuation">)</span> <span class="token operator">+</span>
|
||
<span class="token string">')'</span>
|
||
<span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">hexToRGB</span><span class="token punctuation">(</span><span class="token string">'#27ae60ff'</span><span class="token punctuation">);</span> <span class="token comment">// 'rgba(39, 174, 96, 255)'</span>
|
||
<span class="token function">hexToRGB</span><span class="token punctuation">(</span><span class="token string">'27ae60'</span><span class="token punctuation">);</span> <span class="token comment">// 'rgb(39, 174, 96)'</span>
|
||
<span class="token function">hexToRGB</span><span class="token punctuation">(</span><span class="token string">'#fff'</span><span class="token punctuation">);</span> <span class="token comment">// 'rgb(255, 255, 255)'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="httpget" class="section double-padded">httpGet</h3><div class="section double-padded"><p>Makes a <code>GET</code> request to the passed URL.</p><p>Use <a href="https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Using_XMLHttpRequest"><code>XMLHttpRequest</code></a> web api to make a <code>get</code> request to the given <code>url</code>. Handle the <code>onload</code> event, by calling the given <code>callback</code> the <code>responseText</code>. Handle the <code>onerror</code> event, by running the provided <code>err</code> function. Omit the third argument, <code>err</code>, to log errors to the console's <code>error</code> stream by default.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">httpGet</span> <span class="token operator">=</span> <span class="token punctuation">(</span>url<span class="token punctuation">,</span> callback<span class="token punctuation">,</span> err <span class="token operator">=</span> console<span class="token punctuation">.</span>error<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> request <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">XMLHttpRequest</span><span class="token punctuation">();</span>
|
||
request<span class="token punctuation">.</span><span class="token function">open</span><span class="token punctuation">(</span><span class="token string">'GET'</span><span class="token punctuation">,</span> url<span class="token punctuation">,</span> <span class="token boolean">true</span><span class="token punctuation">);</span>
|
||
request<span class="token punctuation">.</span><span class="token function-variable function">onload</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token function">callback</span><span class="token punctuation">(</span>request<span class="token punctuation">.</span>responseText<span class="token punctuation">);</span>
|
||
request<span class="token punctuation">.</span><span class="token function-variable function">onerror</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token function">err</span><span class="token punctuation">(</span>request<span class="token punctuation">);</span>
|
||
request<span class="token punctuation">.</span><span class="token function">send</span><span class="token punctuation">();
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">httpGet</span><span class="token punctuation">(</span>
|
||
<span class="token string">'https://jsonplaceholder.typicode.com/posts/1'</span><span class="token punctuation">,</span>
|
||
console<span class="token punctuation">.</span>log
|
||
<span class="token punctuation">);</span> <span class="token comment">/*
|
||
Logs: {
|
||
"userId": 1,
|
||
"id": 1,
|
||
"title": "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
|
||
"body": "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"
|
||
}
|
||
*/</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="httppost" class="section double-padded">httpPost</h3><div class="section double-padded"><p>Makes a <code>POST</code> request to the passed URL.</p><p>Use <a href="https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Using_XMLHttpRequest"><code>XMLHttpRequest</code></a> web api to make a <code>post</code> request to the given <code>url</code>. Set the value of an <code>HTTP</code> request header with <code>setRequestHeader</code> method. Handle the <code>onload</code> event, by calling the given <code>callback</code> the <code>responseText</code>. Handle the <code>onerror</code> event, by running the provided <code>err</code> function. Omit the third argument, <code>data</code>, to send no data to the provided <code>url</code>. Omit the fourth argument, <code>err</code>, to log errors to the console's <code>error</code> stream by default.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">httpPost</span> <span class="token operator">=</span> <span class="token punctuation">(</span>url<span class="token punctuation">,</span> callback<span class="token punctuation">,</span> data <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">,</span> err <span class="token operator">=</span> console<span class="token punctuation">.</span>error<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> request <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">XMLHttpRequest</span><span class="token punctuation">();</span>
|
||
request<span class="token punctuation">.</span><span class="token function">open</span><span class="token punctuation">(</span><span class="token string">'POST'</span><span class="token punctuation">,</span> url<span class="token punctuation">,</span> <span class="token boolean">true</span><span class="token punctuation">);</span>
|
||
request<span class="token punctuation">.</span><span class="token function">setRequestHeader</span><span class="token punctuation">(</span><span class="token string">'Content-type'</span><span class="token punctuation">,</span> <span class="token string">'application/json; charset=utf-8'</span><span class="token punctuation">);</span>
|
||
request<span class="token punctuation">.</span><span class="token function-variable function">onload</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token function">callback</span><span class="token punctuation">(</span>request<span class="token punctuation">.</span>responseText<span class="token punctuation">);</span>
|
||
request<span class="token punctuation">.</span><span class="token function-variable function">onerror</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token function">err</span><span class="token punctuation">(</span>request<span class="token punctuation">);</span>
|
||
request<span class="token punctuation">.</span><span class="token function">send</span><span class="token punctuation">(</span>data<span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token keyword">const</span> newPost <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
userId<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
|
||
id<span class="token punctuation">:</span> <span class="token number">1337</span><span class="token punctuation">,</span>
|
||
title<span class="token punctuation">:</span> <span class="token string">'Foo'</span><span class="token punctuation">,</span>
|
||
body<span class="token punctuation">:</span> <span class="token string">'bar bar bar'</span>
|
||
<span class="token punctuation">};</span>
|
||
<span class="token keyword">const</span> data <span class="token operator">=</span> JSON<span class="token punctuation">.</span><span class="token function">stringify</span><span class="token punctuation">(</span>newPost<span class="token punctuation">);</span>
|
||
<span class="token function">httpPost</span><span class="token punctuation">(</span>
|
||
<span class="token string">'https://jsonplaceholder.typicode.com/posts'</span><span class="token punctuation">,</span>
|
||
console<span class="token punctuation">.</span>log<span class="token punctuation">,</span>
|
||
data
|
||
<span class="token punctuation">);</span> <span class="token comment">/*
|
||
Logs: {
|
||
"userId": 1,
|
||
"id": 1337,
|
||
"title": "Foo",
|
||
"body": "bar bar bar"
|
||
}
|
||
*/</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="prettybytes" class="section double-padded">prettyBytes</h3><div class="section double-padded"><p>Converts a number in bytes to a human-readable string.</p><p>Use an array dictionary of units to be accessed based on the exponent. Use <code>Number.toPrecision()</code> to truncate the number to a certain number of digits. Return the prettified string by building it up, taking into account the supplied options and whether it is negative or not. Omit the second argument, <code>precision</code>, to use a default precision of <code>3</code> digits. Omit the third argument, <code>addSpace</code>, to add space between the number and unit by default.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">prettyBytes</span> <span class="token operator">=</span> <span class="token punctuation">(</span>num<span class="token punctuation">,</span> precision <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">,</span> addSpace <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> UNITS <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">'B'</span><span class="token punctuation">,</span> <span class="token string">'KB'</span><span class="token punctuation">,</span> <span class="token string">'MB'</span><span class="token punctuation">,</span> <span class="token string">'GB'</span><span class="token punctuation">,</span> <span class="token string">'TB'</span><span class="token punctuation">,</span> <span class="token string">'PB'</span><span class="token punctuation">,</span> <span class="token string">'EB'</span><span class="token punctuation">,</span> <span class="token string">'ZB'</span><span class="token punctuation">,</span> <span class="token string">'YB'</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">if</span> <span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">abs</span><span class="token punctuation">(</span>num<span class="token punctuation">)</span> <span class="token operator"><</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">return</span> num <span class="token operator">+</span> <span class="token punctuation">(</span>addSpace <span class="token operator">?</span> <span class="token string">' '</span> <span class="token punctuation">:</span> <span class="token string">''</span><span class="token punctuation">)</span> <span class="token operator">+</span> UNITS<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">const</span> exponent <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">min</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">log10</span><span class="token punctuation">(</span>num <span class="token operator"><</span> <span class="token number">0</span> <span class="token operator">? -</span>num <span class="token punctuation">:</span> num<span class="token punctuation">)</span> <span class="token operator">/</span> <span class="token number">3</span><span class="token punctuation">),</span> UNITS<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">const</span> n <span class="token operator">=</span> <span class="token function">Number</span><span class="token punctuation">(((</span>num <span class="token operator"><</span> <span class="token number">0</span> <span class="token operator">? -</span>num <span class="token punctuation">:</span> num<span class="token punctuation">)</span> <span class="token operator">/</span> <span class="token number">1000</span> <span class="token operator">**</span> exponent<span class="token punctuation">).</span><span class="token function">toPrecision</span><span class="token punctuation">(</span>precision<span class="token punctuation">));</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">(</span>num <span class="token operator"><</span> <span class="token number">0</span> <span class="token operator">?</span> <span class="token string">'-'</span> <span class="token punctuation">:</span> <span class="token string">''</span><span class="token punctuation">)</span> <span class="token operator">+</span> n <span class="token operator">+</span> <span class="token punctuation">(</span>addSpace <span class="token operator">?</span> <span class="token string">' '</span> <span class="token punctuation">:</span> <span class="token string">''</span><span class="token punctuation">)</span> <span class="token operator">+</span> UNITS<span class="token punctuation">[</span>exponent<span class="token punctuation">];
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">prettyBytes</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">);</span> <span class="token comment">// "1 KB"</span>
|
||
<span class="token function">prettyBytes</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">27145424323.5821</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">);</span> <span class="token comment">// "-27.145 GB"</span>
|
||
<span class="token function">prettyBytes</span><span class="token punctuation">(</span><span class="token number">123456789</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token boolean">false</span><span class="token punctuation">);</span> <span class="token comment">// "123MB"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="randomhexcolorcode" class="section double-padded">randomHexColorCode</h3><div class="section double-padded"><p>Generates a random hexadecimal color code.</p><p>Use <code>Math.random</code> to generate a random 24-bit(6x4bits) hexadecimal number. Use bit shifting and then convert it to an hexadecimal String using <code>toString(16)</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">randomHexColorCode</span> <span class="token operator">=</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">let</span> n <span class="token operator">=</span> <span class="token punctuation">((</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> <span class="token number">0xfffff</span><span class="token punctuation">)</span> <span class="token operator">|</span> <span class="token number">0</span><span class="token punctuation">).</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token number">16</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> <span class="token string">'#'</span> <span class="token operator">+</span> <span class="token punctuation">(</span>n<span class="token punctuation">.</span>length <span class="token operator">!==</span> <span class="token number">6</span> <span class="token operator">?</span> <span class="token punctuation">((</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> <span class="token number">0xf</span><span class="token punctuation">)</span> <span class="token operator">|</span> <span class="token number">0</span><span class="token punctuation">).</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token number">16</span><span class="token punctuation">)</span> <span class="token operator">+</span> n <span class="token punctuation">:</span> n<span class="token punctuation">);
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">randomHexColorCode</span><span class="token punctuation">();</span> <span class="token comment">// "#e34155"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="rgbtohex" class="section double-padded">RGBToHex</h3><div class="section double-padded"><p>Converts the values of RGB components to a color code.</p><p>Convert given RGB parameters to hexadecimal string using bitwise left-shift operator (<code><<</code>) and <code>toString(16)</code>, then <code>String.padStart(6,'0')</code> to get a 6-digit hexadecimal value.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">RGBToHex</span> <span class="token operator">=</span> <span class="token punctuation">(</span>r<span class="token punctuation">,</span> g<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">((</span>r <span class="token operator"><<</span> <span class="token number">16</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token punctuation">(</span>g <span class="token operator"><<</span> <span class="token number">8</span><span class="token punctuation">)</span> <span class="token operator">+</span> b<span class="token punctuation">).</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token number">16</span><span class="token punctuation">).</span><span class="token function">padStart</span><span class="token punctuation">(</span><span class="token number">6</span><span class="token punctuation">,</span> <span class="token string">'0'</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">RGBToHex</span><span class="token punctuation">(</span><span class="token number">255</span><span class="token punctuation">,</span> <span class="token number">165</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// 'ffa501'</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="timetaken" class="section double-padded">timeTaken</h3><div class="section double-padded"><p>Measures the time taken by a function to execute.</p><p>Use <code>console.time()</code> and <code>console.timeEnd()</code> to measure the difference between the start and end times to determine how long the callback took to execute.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">timeTaken</span> <span class="token operator">=</span> callback <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
console<span class="token punctuation">.</span><span class="token function">time</span><span class="token punctuation">(</span><span class="token string">'timeTaken'</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">const</span> r <span class="token operator">=</span> <span class="token function">callback</span><span class="token punctuation">();</span>
|
||
console<span class="token punctuation">.</span><span class="token function">timeEnd</span><span class="token punctuation">(</span><span class="token string">'timeTaken'</span><span class="token punctuation">);</span>
|
||
<span class="token keyword">return</span> r<span class="token punctuation">;
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">timeTaken</span><span class="token punctuation">(()</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">pow</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">));</span> <span class="token comment">// 1024, (logged): timeTaken: 0.02099609375ms</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="todecimalmark" class="section double-padded">toDecimalMark</h3><div class="section double-padded"><p>Use <code>toLocaleString()</code> to convert a float-point arithmetic to the <a href="https://en.wikipedia.org/wiki/Decimal_mark">Decimal mark</a> form. It makes a comma separated string from a number.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">toDecimalMark</span> <span class="token operator">=</span> num <span class="token operator">=></span> num<span class="token punctuation">.</span><span class="token function">toLocaleString</span><span class="token punctuation">(</span><span class="token string">'en-US'</span><span class="token punctuation">);</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">toDecimalMark</span><span class="token punctuation">(</span><span class="token number">12305030388.9087</span><span class="token punctuation">);</span> <span class="token comment">// "12,305,030,388.909"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="toordinalsuffix" class="section double-padded">toOrdinalSuffix</h3><div class="section double-padded"><p>Adds an ordinal suffix to a number.</p><p>Use the modulo operator (<code>%</code>) to find values of single and tens digits. Find which ordinal pattern digits match. If digit is found in teens pattern, use teens ordinal.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">toOrdinalSuffix</span> <span class="token operator">=</span> num <span class="token operator">=></span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">const</span> int <span class="token operator">=</span> <span class="token function">parseInt</span><span class="token punctuation">(</span>num<span class="token punctuation">),</span>
|
||
digits <span class="token operator">=</span> <span class="token punctuation">[</span>int <span class="token operator">%</span> <span class="token number">10</span><span class="token punctuation">,</span> int <span class="token operator">%</span> <span class="token number">100</span><span class="token punctuation">],</span>
|
||
ordinals <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">'st'</span><span class="token punctuation">,</span> <span class="token string">'nd'</span><span class="token punctuation">,</span> <span class="token string">'rd'</span><span class="token punctuation">,</span> <span class="token string">'th'</span><span class="token punctuation">],</span>
|
||
oPattern <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">],</span>
|
||
tPattern <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">11</span><span class="token punctuation">,</span> <span class="token number">12</span><span class="token punctuation">,</span> <span class="token number">13</span><span class="token punctuation">,</span> <span class="token number">14</span><span class="token punctuation">,</span> <span class="token number">15</span><span class="token punctuation">,</span> <span class="token number">16</span><span class="token punctuation">,</span> <span class="token number">17</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">,</span> <span class="token number">19</span><span class="token punctuation">];</span>
|
||
<span class="token keyword">return</span> oPattern<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>digits<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">])</span> <span class="token operator">&& !</span>tPattern<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>digits<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">])</span>
|
||
<span class="token operator">?</span> int <span class="token operator">+</span> ordinals<span class="token punctuation">[</span>digits<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]
|
||
:</span> int <span class="token operator">+</span> ordinals<span class="token punctuation">[</span><span class="token number">3</span><span class="token punctuation">];
|
||
};</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">toOrdinalSuffix</span><span class="token punctuation">(</span><span class="token string">'123'</span><span class="token punctuation">);</span> <span class="token comment">// "123rd"</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="validatenumber" class="section double-padded">validateNumber</h3><div class="section double-padded"><p>Returns <code>true</code> if the given value is a number, <code>false</code> otherwise.</p><p>Use <code>!isNaN()</code> in combination with <code>parseFloat()</code> to check if the argument is a number. Use <code>isFinite()</code> to check if the number is finite. Use <code>Number()</code> to check if the coercion holds.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">validateNumber</span> <span class="token operator">=</span> n <span class="token operator">=> !</span><span class="token function">isNaN</span><span class="token punctuation">(</span><span class="token function">parseFloat</span><span class="token punctuation">(</span>n<span class="token punctuation">))</span> <span class="token operator">&&</span> <span class="token function">isFinite</span><span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token operator">&&</span> <span class="token function">Number</span><span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token operator">==</span> n<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">validateNumber</span><span class="token punctuation">(</span><span class="token string">'10'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><div class="card fluid"><h3 id="yesno" class="section double-padded">yesNo</h3><div class="section double-padded"><p>Returns <code>true</code> if the string is <code>y</code>/<code>yes</code> or <code>false</code> if the string is <code>n</code>/<code>no</code>.</p><p>Use <code>RegExp.test()</code> to check if the string evaluates to <code>y/yes</code> or <code>n/no</code>. Omit the second argument, <code>def</code> to set the default answer as <code>no</code>.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">yesNo</span> <span class="token operator">=</span> <span class="token punctuation">(</span>val<span class="token punctuation">,</span> def <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">)</span> <span class="token operator">=></span>
|
||
<span class="token regex">/^(y|yes)$/i</span><span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>val<span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token boolean">true</span> <span class="token punctuation">:</span> <span class="token regex">/^(n|no)$/i</span><span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>val<span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token boolean">false</span> <span class="token punctuation">:</span> def<span class="token punctuation">;</span>
|
||
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">yesNo</span><span class="token punctuation">(</span><span class="token string">'Y'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">yesNo</span><span class="token punctuation">(</span><span class="token string">'yes'</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
<span class="token function">yesNo</span><span class="token punctuation">(</span><span class="token string">'No'</span><span class="token punctuation">);</span> <span class="token comment">// false</span>
|
||
<span class="token function">yesNo</span><span class="token punctuation">(</span><span class="token string">'Foo'</span><span class="token punctuation">,</span> <span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// true</span>
|
||
</pre><button class="primary clipboard-copy">📋 Copy to clipboard</button></div></div><button class="scroll-to-top">↑</button><footer><p style="display:inline-block"><strong>30 seconds of code</strong> is licensed under the <a href="https://github.com/Chalarangelo/30-seconds-of-code/blob/master/LICENSE">CC0-1.0</a> license.<br/>Icons made by <a href="https://www.flaticon.com/authors/smashicons">Smashicons</a> from <a href="https://www.flaticon.com/">www.flaticon.com</a> is licensed by <a href="http://creativecommons.org/licenses/by/3.0/">CC 3.0 BY</a>.<br/>Ribbon made by <a href="https://github.com/tholman/github-corners">Tim Holman</a> is licensed by <a href="https://opensource.org/licenses/MIT">The MIT License</a><br/>Built with the <a href="https://minicss.org">mini.css framework</a>.</p></footer></main></div></body></html> |