Adapter
ary
Creates a function that accepts up to n arguments, ignoring any additional arguments.
Call the provided function, fn, with up to n arguments, using Array.slice(0,n) and the spread operator (...).
const ary = (fn, n) => (...args) => fn(...args.slice(0, n)); + }
30 seconds of code Curated collection of useful JavaScript snippets that you can understand in 30 seconds or less.
Adapter
ary
Creates a function that accepts up to
narguments, ignoring any additional arguments.Call the provided function,
fn, with up tonarguments, usingArray.slice(0,n)and the spread operator (...).const ary = (fn, n) => (...args) => fn(...args.slice(0, n));const firstTwoMax = ary(Math.max, 2); [[2, 6, 'a'], [8, 4, 6], [10]].map(x => firstTwoMax(...x)); // [6, 8, 10]call
Given a key and a set of arguments, call them when given a context. Primarily useful in composition.
Use a closure to call a stored key with stored arguments.
const call = (key, ...args) => context => context[key](...args); diff --git a/docs/browser.html b/docs/browser.html index 0ff9df870..f8f06c73d 100644 --- a/docs/browser.html +++ b/docs/browser.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Browser
arrayToHtmlList
Converts the given array elements into
<li>tags and appends them to the list of the given id.Use
Array.map(),document.querySelector(), and an anonymous inner closure to create a list of html tags.const arrayToHtmlList = (arr, listID) => + }
Browser
arrayToHtmlList
Converts the given array elements into
<li>tags and appends them to the list of the given id.Use
Array.map(),document.querySelector(), and an anonymous inner closure to create a list of html tags.const arrayToHtmlList = (arr, listID) => (el => ( (el = document.querySelector('#' + listID)), (el.innerHTML += arr.map(item => `<li>${item}</li>`).join('')) diff --git a/docs/date.html b/docs/date.html index 89bb1edf7..9e0995222 100644 --- a/docs/date.html +++ b/docs/date.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Date
formatDuration
Returns the human readable format of the given number of milliseconds.
Divide
mswith the appropriate values to obtain the appropriate values forday,hour,minute,secondandmillisecond. UseObject.entries()withArray.filter()to keep only non-zero values. UseArray.map()to create the string for each value, pluralizing appropriately. UseString.join(', ')to combine the values into a string.const formatDuration = ms => { + }
Date
formatDuration
Returns the human readable format of the given number of milliseconds.
Divide
mswith the appropriate values to obtain the appropriate values forday,hour,minute,secondandmillisecond. UseObject.entries()withArray.filter()to keep only non-zero values. UseArray.map()to create the string for each value, pluralizing appropriately. UseString.join(', ')to combine the values into a string.const formatDuration = ms => { if (ms < 0) ms = -ms; const time = { day: Math.floor(ms / 86400000), diff --git a/docs/function.html b/docs/function.html index 4b742516f..dbd6d6c4b 100644 --- a/docs/function.html +++ b/docs/function.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Function
attempt
Attempts to invoke a function with the provided arguments, returning either the result or the caught error object.
Use a
try... catchblock to return either the result of the function or an appropriate error.const attempt = (fn, ...args) => { + }
Function
attempt
Attempts to invoke a function with the provided arguments, returning either the result or the caught error object.
Use a
try... catchblock to return either the result of the function or an appropriate error.const attempt = (fn, ...args) => { try { return fn(...args); } catch (e) { diff --git a/docs/index.html b/docs/index.html index 45184b4d3..66cd5ed5e 100644 --- a/docs/index.html +++ b/docs/index.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Array
all
Returns
trueif the provided predicate function returnstruefor all elements in a collection,falseotherwise.Use
Array.every()to test if all elements in the collection returntruebased onfn. Omit the second argument,fn, to useBooleanas a default.const all = (arr, fn = Boolean) => arr.every(fn); + }
Array
all
Returns
trueif the provided predicate function returnstruefor all elements in a collection,falseotherwise.Use
Array.every()to test if all elements in the collection returntruebased onfn. Omit the second argument,fn, to useBooleanas a default.const all = (arr, fn = Boolean) => arr.every(fn);all([4, 2, 3], x => x > 1); // true all([1, 2, 3]); // trueallEqual
Check if all elements in an array are equal.
Use
Array.every()to check if all the elements of the array are the same as the first one.const allEqual = arr => arr.every(val => val === arr[0]); diff --git a/docs/math.html b/docs/math.html index 7494af1ae..7531fb8ad 100644 --- a/docs/math.html +++ b/docs/math.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Math
approximatelyEqual
Checks if two numbers are approximately equal to each other.
Use
Math.abs()to compare the absolute difference of the two values toepsilon. Omit the third parameter,epsilon, to use a default value of0.001.const approximatelyEqual = (v1, v2, epsilon = 0.001) => Math.abs(v1 - v2) < epsilon; + }
Math
approximatelyEqual
Checks if two numbers are approximately equal to each other.
Use
Math.abs()to compare the absolute difference of the two values toepsilon. Omit the third parameter,epsilon, to use a default value of0.001.const approximatelyEqual = (v1, v2, epsilon = 0.001) => Math.abs(v1 - v2) < epsilon;approximatelyEqual(Math.PI / 2.0, 1.5708); // trueaverage
Returns the average of two or more numbers.
Use
Array.reduce()to add each value to an accumulator, initialized with a value of0, divide by thelengthof the array.const average = (...nums) => nums.reduce((acc, val) => acc + val, 0) / nums.length;average(...[1, 2, 3]); // 2 diff --git a/docs/node.html b/docs/node.html index 269c45247..77b1453e6 100644 --- a/docs/node.html +++ b/docs/node.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Node
atob
Decodes a string of data which has been encoded using base-64 encoding.
Create a
Bufferfor the given string with base-64 encoding and useBuffer.toString('binary')to return the decoded string.const atob = str => new Buffer(str, 'base64').toString('binary'); + }
Node
atob
Decodes a string of data which has been encoded using base-64 encoding.
Create a
Bufferfor the given string with base-64 encoding and useBuffer.toString('binary')to return the decoded string.const atob = str => new Buffer(str, 'base64').toString('binary');atob('Zm9vYmFy'); // 'foobar'btoa
Creates a base-64 encoded ASCII string from a String object in which each character in the string is treated as a byte of binary data.
Create a
Bufferfor the given string with binary encoding and useBuffer.toString('base64')to return the encoded string.const btoa = str => new Buffer(str, 'binary').toString('base64');btoa('foobar'); // 'Zm9vYmFy' diff --git a/docs/object.html b/docs/object.html index d9eabd29a..e2d946278 100644 --- a/docs/object.html +++ b/docs/object.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Object
bindAll
Binds methods of an object to the object itself, overwriting the existing method.
Use
Array.forEach()to return afunctionthat usesFunction.apply()to apply the given context (obj) tofnfor each function specified.const bindAll = (obj, ...fns) => + }
Object
bindAll
Binds methods of an object to the object itself, overwriting the existing method.
Use
Array.forEach()to return afunctionthat usesFunction.apply()to apply the given context (obj) tofnfor each function specified.const bindAll = (obj, ...fns) => fns.forEach( fn => ( (f = obj[fn]), diff --git a/docs/string.html b/docs/string.html index 9602c7e76..65d5625e8 100644 --- a/docs/string.html +++ b/docs/string.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
String
byteSize
Returns the length of a string in bytes.
Convert a given string to a
BlobObject and find itssize.const byteSize = str => new Blob([str]).size; + }
String
byteSize
Returns the length of a string in bytes.
Convert a given string to a
BlobObject and find itssize.const byteSize = str => new Blob([str]).size;byteSize('😀'); // 4 byteSize('Hello World'); // 11capitalize
Capitalizes the first letter of a string.
Use array destructuring and
String.toUpperCase()to capitalize first letter,...restto get array of characters after first letter and thenArray.join('')to make it a string again. Omit thelowerRestparameter to keep the rest of the string intact, or set it totrueto convert to lowercase.const capitalize = ([first, ...rest], lowerRest = false) => @@ -129,6 +129,9 @@fromCamelCase('someDatabaseFieldName', ' '); // 'some database field name' fromCamelCase('someLabelThatNeedsToBeCamelized', '-'); // 'some-label-that-needs-to-be-camelized' fromCamelCase('someJavascriptProperty', '_'); // 'some_javascript_property' +indentString
Indents each line in the provided string.
Use
String.replaceand a regular expression to add the character specified byindentcounttimes at the start of each line. Omit the third parameter,indent, to use a default indentation character of' '.const indentString = (str, count, indent = ' ') => str.replace(/^/gm, indent.repeat(count)); +indentString('Lorem\nIpsum', 2); // ' Lorem\n Ipsum' +indentString('Lorem\nIpsum', 2, '_'); // '__Lorem\n__Ipsum'isAbsoluteURL
Returns
trueif the given string is an absolute URL,falseotherwise.Use a regular expression to test if the string is an absolute URL.
const isAbsoluteURL = str => /^[a-z][a-z0-9+.-]*:/.test(str);isAbsoluteURL('https://google.com'); // true isAbsoluteURL('ftp://www.myserver.net'); // true diff --git a/docs/type.html b/docs/type.html index d8139d60a..b6e7cdb29 100644 --- a/docs/type.html +++ b/docs/type.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Type
getType
Returns the native type of a value.
Returns lowercased constructor name of value,
"undefined"or"null"if value isundefinedornull.const getType = v => + }
Type
getType
Returns the native type of a value.
Returns lowercased constructor name of value,
"undefined"or"null"if value isundefinedornull.const getType = v => v === undefined ? 'undefined' : v === null ? 'null' : v.constructor.name.toLowerCase();getType(new Set([1, 2, 3])); // 'set'is
Checks if the provided value is of the specified type.
Ensure the value is not
undefinedornullusingArray.includes(), and compare theconstructorproperty on the value withtypeto check if the provided value is of the specifiedtype.const is = (type, val) => ![, null].includes(val) && val.constructor === type; diff --git a/docs/utility.html b/docs/utility.html index 266ab3fa5..fdf5d16fb 100644 --- a/docs/utility.html +++ b/docs/utility.html @@ -73,7 +73,7 @@ },1700); } }, false); - }
Utility
castArray
Casts the provided value as an array if it's not one.
Use
Array.isArray()to determine ifvalis an array and return it as-is or encapsulated in an array accordingly.const castArray = val => (Array.isArray(val) ? val : [val]); + }
Utility
castArray
Casts the provided value as an array if it's not one.
Use
Array.isArray()to determine ifvalis an array and return it as-is or encapsulated in an array accordingly.const castArray = val => (Array.isArray(val) ? val : [val]);castArray('foo'); // ['foo'] castArray([1]); // [1]cloneRegExp
Clones a regular expression.
Use
new RegExp(),RegExp.sourceandRegExp.flagsto clone the given regular expression.const cloneRegExp = regExp => new RegExp(regExp.source, regExp.flags); diff --git a/snippets/indentString.md b/snippets/indentString.md index 0fe2502f2..4f716882c 100644 --- a/snippets/indentString.md +++ b/snippets/indentString.md @@ -6,8 +6,7 @@ Use `String.replace` and a regular expression to add the character specified by Omit the third parameter, `indent`, to use a default indentation character of `' '`. ```js -const indentString = (str, count, indent = ' ') => - str.replace(/^/mg, indent.repeat(count)); +const indentString = (str, count, indent = ' ') => str.replace(/^/gm, indent.repeat(count)); ``` ```js