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Merge branch 'master' of https://github.com/Chalarangelo/30-seconds-of-code into patch-1

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David Wu
2017-12-18 12:12:40 +01:00
parent e490889801 afc292d706
commit c41057cc10
17 changed files with 185 additions and 45 deletions
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88
README.md
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@ -30,6 +30,7 @@
* [`initializeArrayWithValues`](#initializearraywithvalues)
* [`intersection`](#intersection)
* [`last`](#last)
* [`mapObject`](#mapobject)
* [`nthElement`](#nthelement)
* [`pick`](#pick)
* [`pull`](#pull)
@ -47,7 +48,7 @@
### Browser
* [`bottomVisible`](#bottomvisible)
* [`current-URL`](#current-url)
* [`currentURL`](#currenturl)
* [`elementIsVisibleInViewport`](#elementisvisibleinviewport)
* [`getScrollPosition`](#getscrollposition)
* [`getURLParameters`](#geturlparameters)
@ -103,6 +104,7 @@
* [`objectFromPairs`](#objectfrompairs)
* [`objectToPairs`](#objecttopairs)
* [`shallowClone`](#shallowclone)
* [`truthCheckCollection`](#truthcheckcollection)
### String
* [`anagrams`](#anagrams)
@ -116,6 +118,8 @@
* [`truncateString`](#truncatestring)
### Utility
* [`coalesce`](#coalesce)
* [`coalesceFactory`](#coalescefactory)
* [`extendHex`](#extendhex)
* [`getType`](#gettype)
* [`hexToRGB`](#hextorgb)
@ -191,7 +195,7 @@ const compact = (arr) => arr.filter(Boolean);
### countOccurrences
Counts the occurences of a value in an array.
Counts the occurrences of a value in an array.
Use `Array.reduce()` to increment a counter each time you encounter the specific value inside the array.
@ -362,7 +366,7 @@ const initial = arr => arr.slice(0, -1);
### initializeArrayWithRange
Initialized an array containing the numbers in the specified range.
Initializes an array containing the numbers in the specified range.
Use `Array(end-start)` to create an array of the desired length, `Array.map()` to fill with the desired values in a range.
You can omit `start` to use a default value of `0`.
@ -415,6 +419,23 @@ const last = arr => arr[arr.length - 1];
[⬆ back to top](#table-of-contents)
### mapObject
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.
Use an anonymous inner function scope to declare an undefined memory space, using closures to store a return value. Use a new `Array` to stor 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).
```js
const mapObject = (arr, fn) =>
(a => (a = [arr, arr.map(fn)], a[0].reduce( (acc,val,ind) => (acc[val] = a[1][ind], acc), {}) )) ( );
/*
const squareIt = arr => mapObject(arr, a => a*a)
squareIt([1,2,3]) // { 1: 1, 2: 4, 3: 9 }
*/
```
[⬆ back to top](#table-of-contents)
### nthElement
Returns the nth element of an array.
@ -554,7 +575,7 @@ const tail = arr => arr.length > 1 ? arr.slice(1) : arr;
### take
Returns an array with n elements removed from the beggining.
Returns an array with n elements removed from the beginning.
Use `Array.slice()` to create a slice of the array with `n` elements taken from the beginning.
@ -1280,7 +1301,7 @@ Returns an array of lines from the specified file.
Use `readFileSync` function in `fs` node package to create a `Buffer` from a file.
convert buffer to string using `toString(encoding)` function.
creating an array from contents of file by `split`ing file content line by line(each `\n`).
creating an array from contents of file by `split`ing file content line by line (each `\n`).
```js
const fs = require('fs');
@ -1304,7 +1325,7 @@ const readFileLines = filename => fs.readFileSync(filename).toString('UTF8').spl
Removes any properties except the ones specified from a JSON object.
Use `Object.keys()` method to loop over given json object and deleting keys that are not `include`d in given array.
also if you give it a special key(`childIndicator`) it will search deeply inside it to apply function to inner objects too.
Also if you give it a special key (`childIndicator`) it will search deeply inside it to apply function to inner objects too.
```js
const cleanObj = (obj, keysToKeep = [], childIndicator) => {
@ -1366,6 +1387,19 @@ a === b -> false
*/
```
[⬆ back to top](#table-of-contents)
### truthCheckCollection
Checks if the predicate (second argument) is truthy on all elements of a collection (first argument).
Use `Array.every()` to check if each passed object has the specified property and if it returns a truthy value.
```js
truthCheckCollection = (collection, pre) => (collection.every(obj => obj[pre]));
// truthCheckCollection([{"user": "Tinky-Winky", "sex": "male"}, {"user": "Dipsy", "sex": "male"}], "sex") -> true
```
[⬆ back to top](#table-of-contents)
## String
@ -1394,7 +1428,7 @@ const anagrams = str => {
Capitalizes the first letter of a string.
Use destructuring and `toUpperCase()` to capitalize first letter, `...rest` to get array of characters after first letter and then `Array.join('')` to make it a string again.
Omit the `lowerRest` parameter to keep the rest of the string intact, or set it to `true` to convert to lower case.
Omit the `lowerRest` parameter to keep the rest of the string intact, or set it to `true` to convert to lowercase.
```js
const capitalize = ([first,...rest], lowerRest = false) =>
@ -1436,7 +1470,7 @@ const escapeRegExp = str => str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
Converts a string from camelcase.
Use `replace()` to remove underscores, hyphens and spaces and convert words to camelcase.
Omit the scond argument to use a default separator of `_`.
Omit the second argument to use a default separator of `_`.
```js
const fromCamelCase = (str, separator = '_') =>
@ -1510,6 +1544,33 @@ const truncateString = (str, num) =>
[⬆ back to top](#table-of-contents)
## Utility
### coalesce
Returns the first non-null/undefined argument.
Use `Array.find()` to return the first non `null`/`undefined` argument.
```js
const coalesce = (...args) => args.find(_ => ![undefined, null].includes(_))
// coalesce(null,undefined,"",NaN, "Waldo") -> ""
```
[⬆ back to top](#table-of-contents)
### coalesceFactory
Returns a customized coalesce function that returns the first argument that returns `true` from the provided argument validation function.
Use `Array.find()` to return the first argument that returns `true` from the provided argument validation function.
```js
const coalesceFactory = valid => (...args) => args.find(valid);
// const customCoalesce = coalesceFactory(_ => ![null, undefined, "", NaN].includes(_))
// customCoalesce(undefined, null, NaN, "", "Waldo") //-> "Waldo"
```
[⬆ back to top](#table-of-contents)
### extendHex
Extends a 3-digit color code to a 6-digit color code.
@ -1529,7 +1590,7 @@ const extendHex = shortHex =>
Returns the native type of a value.
Returns lower-cased constructor name of value, "undefined" or "null" if value is undefined or null
Returns lowercased constructor name of value, "undefined" or "null" if value is undefined or null
```js
const getType = v =>
@ -1547,12 +1608,11 @@ Use bitwise right-shift operator and mask bits with `&` (and) operator to conver
```js
const hexToRgb = hex => {
const extendHex = shortHex =>
const extendHex = shortHex =>
'#' + shortHex.slice(shortHex.startsWith('#') ? 1 : 0).split('').map(x => x+x).join('');
return hex.slice(1).length==3 ?
`rgb(${parseInt(extendHex(hex).slice(1), 16) >> 16}, ${(parseInt(extendHex(hex).slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(extendHex(hex).slice(1), 16) & 0x0000ff})`:
`rgb(${parseInt(hex.slice(1), 16) >> 16}, ${(parseInt(hex.slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(hex.slice(1), 16) & 0x0000ff})`;
}
const extendedHex = hex.slice(hex.startsWith('#') ? 1 : 0).length === 3 ? extendHex(hex) : hex;
return `rgb(${parseInt(extendedHex.slice(1), 16) >> 16}, ${(parseInt(extendedHex.slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(extendedHex.slice(1), 16) & 0x0000ff})`;
}
// hexToRgb('#27ae60') -> 'rgb(39, 174, 96)'
// hexToRgb('#acd') -> 'rgb(170, 204, 221)'
```

66
docs/index.html
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@ -53,6 +53,7 @@
<a class="sublink-1" href="#initializearraywithvalues">initializeArrayWithValues</a>
<a class="sublink-1" href="#intersection">intersection</a>
<a class="sublink-1" href="#last">last</a>
<a class="sublink-1" href="#mapobject">mapObject</a>
<a class="sublink-1" href="#nthelement">nthElement</a>
<a class="sublink-1" href="#pick">pick</a>
<a class="sublink-1" href="#pull">pull</a>
@ -70,7 +71,7 @@
<h3>Browser
</h3><a class="sublink-1" href="#bottomvisible">bottomVisible</a>
<a class="sublink-1" href="#current-url">current-URL</a>
<a class="sublink-1" href="#currenturl">currentURL</a>
<a class="sublink-1" href="#elementisvisibleinviewport">elementIsVisibleInViewport</a>
<a class="sublink-1" href="#getscrollposition">getScrollPosition</a>
<a class="sublink-1" href="#geturlparameters">getURLParameters</a>
@ -126,6 +127,7 @@
<a class="sublink-1" href="#objectfrompairs">objectFromPairs</a>
<a class="sublink-1" href="#objecttopairs">objectToPairs</a>
<a class="sublink-1" href="#shallowclone">shallowClone</a>
<a class="sublink-1" href="#truthcheckcollection">truthCheckCollection</a>
<h3>String
</h3><a class="sublink-1" href="#anagrams">anagrams</a>
@ -139,7 +141,9 @@
<a class="sublink-1" href="#truncatestring">truncateString</a>
<h3>Utility
</h3><a class="sublink-1" href="#extendhex">extendHex</a>
</h3><a class="sublink-1" href="#coalesce">coalesce</a>
<a class="sublink-1" href="#coalescefactory">coalesceFactory</a>
<a class="sublink-1" href="#extendhex">extendHex</a>
<a class="sublink-1" href="#gettype">getType</a>
<a class="sublink-1" href="#hextorgb">hexToRGB</a>
<a class="sublink-1" href="#isarray">isArray</a>
@ -184,7 +188,7 @@ If the original array can't be split evenly, the final chunk will contain the re
// compact([0, 1, false, 2, '', 3, 'a', 'e'*23, NaN, 's', 34]) -&gt; [ 1, 2, 3, 'a', 's', 34 ]
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="countoccurrences">countOccurrences</h3></div><div class="section double-padded">
<p>Counts the occurences of a value in an array.</p>
<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><code class="language-js">const countOccurrences = (arr, value) =&gt; arr.reduce((a, v) =&gt; v === value ? a + 1 : a + 0, 0);
// countOccurrences([1,1,2,1,2,3], 1) -&gt; 3
@ -271,7 +275,7 @@ Use <code>Array.reduce()</code> to create an object, where the keys are produced
// initial([1,2,3]) -&gt; [1,2]
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="initializearraywithrange">initializeArrayWithRange</h3></div><div class="section double-padded">
<p>Initialized an array containing the numbers in the specified range.</p>
<p>Initializes an array containing the numbers in the specified range.</p>
<p>Use <code>Array(end-start)</code> to create an array of the desired length, <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>.</p>
<pre><code class="language-js">const initializeArrayWithRange = (end, start = 0) =&gt;
@ -297,6 +301,16 @@ You can omit <code>value</code> to use a default value of <code>0</code>.</p>
<pre><code class="language-js">const last = arr =&gt; arr[arr.length - 1];
// last([1,2,3]) -&gt; 3
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="mapobject">mapObject</h3></div><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 stor 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><code class="language-js">const mapObject = (arr, fn) =&gt;
(a =&gt; (a = [arr, arr.map(fn)], a[0].reduce( (acc,val,ind) =&gt; (acc[val] = a[1][ind], acc), {}) )) ( );
/*
const squareIt = arr =&gt; mapObject(arr, a =&gt; a*a)
squareIt([1,2,3]) // { 1: 1, 2: 4, 3: 9 }
*/
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="nthelement">nthElement</h3></div><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.
@ -372,7 +386,7 @@ This method also works with strings.</p>
// tail([1]) -&gt; [1]
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="take">take</h3></div><div class="section double-padded">
<p>Returns an array with n elements removed from the beggining.</p>
<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><code class="language-js">const take = (arr, n = 1) =&gt; arr.slice(0, n);
// take([1, 2, 3], 5) -&gt; [1, 2, 3]
@ -419,7 +433,7 @@ If lengths of the argument-arrays vary, <code>undefined</code> is used where no
document.documentElement.clientHeight + window.scrollY &gt;= document.documentElement.scrollHeight || document.documentElement.clientHeight;
// bottomVisible() -&gt; true
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="current-url">currentURL</h3></div><div class="section double-padded">
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="currenturl">currentURL</h3></div><div class="section double-padded">
<p>Returns the current URL.</p>
<p>Use <code>window.location.href</code> to get current URL.</p>
<pre><code class="language-js">const currentURL = () =&gt; window.location.href;
@ -780,7 +794,7 @@ const JSONToFile = (obj, filename) =&gt; fs.writeFile(`${filename}.json`, JSON.s
<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>
creating an array from contents of file by <code>split</code>ing file content line by line (each <code>\n</code>).</p>
<pre><code class="language-js">const fs = require('fs');
const readFileLines = filename =&gt; fs.readFileSync(filename).toString('UTF8').split('\n');
/*
@ -797,7 +811,7 @@ console.log(arr) // -&gt; ['line1', 'line2', 'line3']
<div class="card fluid"><div class="section double-padded"><h3 id="cleanobj">cleanObj</h3></div><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 <code>include</code>d in given array.
also if you give it a special key(<code>childIndicator</code>) it will search deeply inside it to apply function to inner objects too.</p>
Also if you give it a special key (<code>childIndicator</code>) it will search deeply inside it to apply function to inner objects too.</p>
<pre><code class="language-js">const cleanObj = (obj, keysToKeep = [], childIndicator) =&gt; {
Object.keys(obj).forEach(key =&gt; {
if (key === childIndicator) {
@ -835,6 +849,12 @@ const b = shallowClone(a);
a === b -&gt; false
*/
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="truthcheckcollection">truthCheckCollection</h3></div><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><code class="language-js">truthCheckCollection = (collection, pre) =&gt; (collection.every(obj =&gt; obj[pre]));
// truthCheckCollection([{&quot;user&quot;: &quot;Tinky-Winky&quot;, &quot;sex&quot;: &quot;male&quot;}, {&quot;user&quot;: &quot;Dipsy&quot;, &quot;sex&quot;: &quot;male&quot;}], &quot;sex&quot;) -&gt; true
</code></pre>
</div></div><br/><h2 style="text-align:center;">String</h2>
<div class="card fluid"><div class="section double-padded"><h3 id="anagrams">anagrams</h3></div><div class="section double-padded">
<p>Generates all anagrams of a string (contains duplicates).</p>
@ -852,7 +872,7 @@ Base cases are for string <code>length</code> equal to <code>2</code> or <code>1
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="capitalize">Capitalize</h3></div><div class="section double-padded">
<p>Capitalizes the first letter of a string.</p>
<p>Use destructuring and <code>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 lower case.</p>
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><code class="language-js">const capitalize = ([first,...rest], lowerRest = false) =&gt;
first.toUpperCase() + (lowerRest ? rest.join('').toLowerCase() : rest.join(''));
// capitalize('myName') -&gt; 'MyName'
@ -873,7 +893,7 @@ Omit the <code>lowerRest</code> parameter to keep the rest of the string intact,
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="fromcamelcase">fromCamelCase</h3></div><div class="section double-padded">
<p>Converts a string from camelcase.</p>
<p>Use <code>replace()</code> to remove underscores, hyphens and spaces and convert words to camelcase.
Omit the scond argument to use a default separator of <code>_</code>.</p>
Omit the second argument to use a default separator of <code>_</code>.</p>
<pre><code class="language-js">const fromCamelCase = (str, separator = '_') =&gt;
str.replace(/([a-z\d])([A-Z])/g, '$1' + separator + '$2')
.replace(/([A-Z]+)([A-Z][a-z\d]+)/g, '$1' + separator + '$2').toLowerCase();
@ -914,7 +934,20 @@ Return the string truncated to the desired length, with <code>...</code> appende
// truncateString('boomerang', 7) -&gt; 'boom...'
</code></pre>
</div></div><br/><h2 style="text-align:center;">Utility</h2>
<div class="card fluid"><div class="section double-padded"><h3 id="extendhex">extendHex</h3></div><div class="section double-padded">
<div class="card fluid"><div class="section double-padded"><h3 id="coalesce">coalesce</h3></div><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><code class="language-js">const coalesce = (...args) =&gt; args.find(_ =&gt; ![undefined, null].includes(_))
// coalesce(null,undefined,&quot;&quot;,NaN, &quot;Waldo&quot;) -&gt; &quot;&quot;
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="coalescefactory">coalesceFactory</h3></div><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><code class="language-js">const coalesceFactory = valid =&gt; (...args) =&gt; args.find(valid);
// const customCoalesce = coalesceFactory(_ =&gt; ![null, undefined, &quot;&quot;, NaN].includes(_))
// customCoalesce(undefined, null, NaN, &quot;&quot;, &quot;Waldo&quot;) //-&gt; &quot;Waldo&quot;
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="extendhex">extendHex</h3></div><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>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>
@ -925,7 +958,7 @@ Return the string truncated to the desired length, with <code>...</code> appende
</code></pre>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="gettype">getType</h3></div><div class="section double-padded">
<p>Returns the native type of a value.</p>
<p>Returns lower-cased constructor name of value, &quot;undefined&quot; or &quot;null&quot; if value is undefined or null</p>
<p>Returns lowercased constructor name of value, &quot;undefined&quot; or &quot;null&quot; if value is undefined or null</p>
<pre><code class="language-js">const getType = v =&gt;
v === undefined ? 'undefined' : v === null ? 'null' : v.constructor.name.toLowerCase();
// getType(new Set([1,2,3])) -&gt; &quot;set&quot;
@ -934,12 +967,11 @@ Return the string truncated to the desired length, with <code>...</code> appende
<p>Converts a colorcode to a <code>rgb()</code> string.</p>
<p>Use bitwise right-shift operator and mask bits with <code>&amp;</code> (and) operator to convert a hexadecimal color code (prefixed with <code>#</code>) to a string with the RGB values. In case it's a 3-digit-colorcode, do the same with the 6-digit-colorcode extended by the extendHex() function (ref. <code>extendHex</code> snippet)</p>
<pre><code class="language-js">const hexToRgb = hex =&gt; {
const extendHex = shortHex =&gt;
const extendHex = shortHex =&gt;
'#' + shortHex.slice(shortHex.startsWith('#') ? 1 : 0).split('').map(x =&gt; x+x).join('');
return hex.slice(1).length==3 ?
`rgb(${parseInt(extendHex(hex).slice(1), 16) &gt;&gt; 16}, ${(parseInt(extendHex(hex).slice(1), 16) &amp; 0x00ff00) &gt;&gt; 8}, ${parseInt(extendHex(hex).slice(1), 16) &amp; 0x0000ff})`:
`rgb(${parseInt(hex.slice(1), 16) &gt;&gt; 16}, ${(parseInt(hex.slice(1), 16) &amp; 0x00ff00) &gt;&gt; 8}, ${parseInt(hex.slice(1), 16) &amp; 0x0000ff})`;
}
const extendedHex = hex.slice(hex.startsWith('#') ? 1 : 0).length === 3 ? extendHex(hex) : hex;
return `rgb(${parseInt(extendedHex.slice(1), 16) &gt;&gt; 16}, ${(parseInt(extendedHex.slice(1), 16) &amp; 0x00ff00) &gt;&gt; 8}, ${parseInt(extendedHex.slice(1), 16) &amp; 0x0000ff})`;
}
// hexToRgb('#27ae60') -&gt; 'rgb(39, 174, 96)'
// hexToRgb('#acd') -&gt; 'rgb(170, 204, 221)'
</code></pre>

2
snippets/capitalize.md
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@ -3,7 +3,7 @@
Capitalizes the first letter of a string.
Use destructuring and `toUpperCase()` to capitalize first letter, `...rest` to get array of characters after first letter and then `Array.join('')` to make it a string again.
Omit the `lowerRest` parameter to keep the rest of the string intact, or set it to `true` to convert to lower case.
Omit the `lowerRest` parameter to keep the rest of the string intact, or set it to `true` to convert to lowercase.
```js
const capitalize = ([first,...rest], lowerRest = false) =>

2
snippets/cleanObj.md
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@ -3,7 +3,7 @@
Removes any properties except the ones specified from a JSON object.
Use `Object.keys()` method to loop over given json object and deleting keys that are not `include`d in given array.
also if you give it a special key(`childIndicator`) it will search deeply inside it to apply function to inner objects too.
Also if you give it a special key (`childIndicator`) it will search deeply inside it to apply function to inner objects too.
```js
const cleanObj = (obj, keysToKeep = [], childIndicator) => {

10
snippets/coalesce.md Normal file
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@ -0,0 +1,10 @@
### coalesce
Returns the first non-null/undefined argument.
Use `Array.find()` to return the first non `null`/`undefined` argument.
```js
const coalesce = (...args) => args.find(_ => ![undefined, null].includes(_))
// coalesce(null,undefined,"",NaN, "Waldo") -> ""
```

11
snippets/coalesceFactory.md Normal file
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@ -0,0 +1,11 @@
### coalesceFactory
Returns a customized coalesce function that returns the first argument that returns `true` from the provided argument validation function.
Use `Array.find()` to return the first argument that returns `true` from the provided argument validation function.
```js
const coalesceFactory = valid => (...args) => args.find(valid);
// const customCoalesce = coalesceFactory(_ => ![null, undefined, "", NaN].includes(_))
// customCoalesce(undefined, null, NaN, "", "Waldo") //-> "Waldo"
```

2
snippets/countOccurrences.md
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@ -1,6 +1,6 @@
### countOccurrences
Counts the occurences of a value in an array.
Counts the occurrences of a value in an array.
Use `Array.reduce()` to increment a counter each time you encounter the specific value inside the array.

0
snippets/current-URL.md → snippets/currentURL.md
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2
snippets/fromCamelCase.md
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@ -3,7 +3,7 @@
Converts a string from camelcase.
Use `replace()` to remove underscores, hyphens and spaces and convert words to camelcase.
Omit the scond argument to use a default separator of `_`.
Omit the second argument to use a default separator of `_`.
```js
const fromCamelCase = (str, separator = '_') =>

2
snippets/getType.md
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@ -2,7 +2,7 @@
Returns the native type of a value.
Returns lower-cased constructor name of value, "undefined" or "null" if value is undefined or null
Returns lowercased constructor name of value, "undefined" or "null" if value is undefined or null
```js
const getType = v =>

9
snippets/hexToRGB.md
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@ -6,12 +6,11 @@ Use bitwise right-shift operator and mask bits with `&` (and) operator to conver
```js
const hexToRgb = hex => {
const extendHex = shortHex =>
const extendHex = shortHex =>
'#' + shortHex.slice(shortHex.startsWith('#') ? 1 : 0).split('').map(x => x+x).join('');
return hex.slice(1).length==3 ?
`rgb(${parseInt(extendHex(hex).slice(1), 16) >> 16}, ${(parseInt(extendHex(hex).slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(extendHex(hex).slice(1), 16) & 0x0000ff})`:
`rgb(${parseInt(hex.slice(1), 16) >> 16}, ${(parseInt(hex.slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(hex.slice(1), 16) & 0x0000ff})`;
}
const extendedHex = hex.slice(hex.startsWith('#') ? 1 : 0).length === 3 ? extendHex(hex) : hex;
return `rgb(${parseInt(extendedHex.slice(1), 16) >> 16}, ${(parseInt(extendedHex.slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(extendedHex.slice(1), 16) & 0x0000ff})`;
}
// hexToRgb('#27ae60') -> 'rgb(39, 174, 96)'
// hexToRgb('#acd') -> 'rgb(170, 204, 221)'
```

2
snippets/initializeArrayWithRange.md
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@ -1,6 +1,6 @@
### initializeArrayWithRange
Initialized an array containing the numbers in the specified range.
Initializes an array containing the numbers in the specified range.
Use `Array(end-start)` to create an array of the desired length, `Array.map()` to fill with the desired values in a range.
You can omit `start` to use a default value of `0`.

14
snippets/mapObject.md Normal file
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@ -0,0 +1,14 @@
### mapObject
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.
Use an anonymous inner function scope to declare an undefined memory space, using closures to store a return value. Use a new `Array` to stor 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).
```js
const mapObject = (arr, fn) =>
(a => (a = [arr, arr.map(fn)], a[0].reduce( (acc,val,ind) => (acc[val] = a[1][ind], acc), {}) )) ( );
/*
const squareIt = arr => mapObject(arr, a => a*a)
squareIt([1,2,3]) // { 1: 1, 2: 4, 3: 9 }
*/
```

2
snippets/readFileLines.md
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@ -4,7 +4,7 @@ Returns an array of lines from the specified file.
Use `readFileSync` function in `fs` node package to create a `Buffer` from a file.
convert buffer to string using `toString(encoding)` function.
creating an array from contents of file by `split`ing file content line by line(each `\n`).
creating an array from contents of file by `split`ing file content line by line (each `\n`).
```js
const fs = require('fs');

2
snippets/take.md
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@ -1,6 +1,6 @@
### take
Returns an array with n elements removed from the beggining.
Returns an array with n elements removed from the beginning.
Use `Array.slice()` to create a slice of the array with `n` elements taken from the beginning.

10
snippets/truthCheckCollection.md Normal file
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### truthCheckCollection
Checks if the predicate (second argument) is truthy on all elements of a collection (first argument).
Use `Array.every()` to check if each passed object has the specified property and if it returns a truthy value.
```js
truthCheckCollection = (collection, pre) => (collection.every(obj => obj[pre]));
// truthCheckCollection([{"user": "Tinky-Winky", "sex": "male"}, {"user": "Dipsy", "sex": "male"}], "sex") -> true
```

6
tag_database
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@ -9,11 +9,13 @@ capitalizeEveryWord:string
chainAsync:function
chunk:array
cleanObj:object
coalesce:utility
coalesceFactory:utility
collatz:math
compact:array
compose:function
countOccurrences:array
current-URL:browser
currentURL:browser
curry:function
deepFlatten:array
difference:array
@ -57,6 +59,7 @@ JSONToDate:date
JSONToFile:node
last:array
lcm:math
mapObject:array
median:math
nthElement:array
objectFromPairs:object
@ -95,6 +98,7 @@ toCamelCase:string
toEnglishDate:date
toOrdinalSuffix:utility
truncateString:string
truthCheckCollection:object
union:array
UUIDGenerator:utility
validateEmail:utility