core-js
As advertising: the author is looking for a good job :)
Modular standard library for JavaScript. Includes polyfills for ECMAScript 5, ECMAScript 6: promises, symbols, collections, iterators, typed arrays, ECMAScript 7+ proposals, setImmediate, etc. Some additional features such as dictionaries or extended partial application. You can require only needed features or use it without global namespace pollution.
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
'*'.repeat(10); // => '**********'
Promise.resolve(32).then(x => console.log(x)); // => 32
setImmediate(x => console.log(x), 42); // => 42Without global namespace pollution:
var core = require('core-js/library'); // With a modular system, otherwise use global `core`
core.Array.from(new core.Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
core.String.repeat('*', 10); // => '**********'
core.Promise.resolve(32).then(x => console.log(x)); // => 32
core.setImmediate(x => console.log(x), 42); // => 42Index
- Usage
- Supported engines
- Features
- ECMAScript 5
- ECMAScript 6
- ECMAScript 6: Object
- ECMAScript 6: Function
- ECMAScript 6: Array
- ECMAScript 6: String
- ECMAScript 6: RegExp
- ECMAScript 6: Number
- ECMAScript 6: Math
- ECMAScript 6: Date
- ECMAScript 6: Promise
- ECMAScript 6: Symbol
- ECMAScript 6: Collections
- ECMAScript 6: Typed Arrays
- ECMAScript 6: Reflect
- ECMAScript 7+ proposals
- stage 4 proposals
- stage 3 proposals
- stage 2 proposals
- stage 1 proposals
- stage 0 proposals
- pre-stage 0 proposals
- Web standards
- setTimeout / setInterval
- setImmediate
- iterable DOM collections
- Non-standard
- Object
- Dict
- partial application
- Number Iterator
- escaping strings
- delay
- helpers for iterators
- Missing polyfills
- Changelog
Usage
Basic
npm i core-js
bower install core.js// Default
require('core-js');
// Without global namespace pollution
var core = require('core-js/library');
// Shim only
require('core-js/shim');If you need complete build for browser, use builds from core-js/client path:
- default: Includes all features, standard and non-standard.
- as a library: Like "default", but does not pollute the global namespace (see 2nd example at the top).
- shim only: Only includes the standard methods.
Warning: if you use core-js with the extension of native objects, require all needed core-js modules at the beginning of entry point of your application, otherwise, conflicts may occur.
CommonJS
You can require only needed modules.
require('core-js/fn/set');
require('core-js/fn/array/from');
require('core-js/fn/array/find-index');
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
[1, 2, NaN, 3, 4].findIndex(isNaN); // => 2
// or, w/o global namespace pollution:
var Set = require('core-js/library/fn/set');
var from = require('core-js/library/fn/array/from');
var findIndex = require('core-js/library/fn/array/find-index');
from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
findIndex([1, 2, NaN, 3, 4], isNaN); // => 2Available entry points for methods / constructors, as above examples, and namespaces: for example, core-js/es6/array (core-js/library/es6/array) contains all ES6 Array features, core-js/es6 (core-js/library/es6) contains all ES6 features.
Caveats when using CommonJS API:
modulespath is internal API, does not inject all required dependencies and can be changed in minor or patch releases. Use it only for a custom build and / or if you know what are you doing.core-jsis extremely modular and uses a lot of very tiny modules, because of that for usage in browsers bundle upcore-jsinstead of usage loader for each file, otherwise, you will have hundreds of requests.
CommonJS and prototype methods without global namespace pollution
In the library version, we can't pollute prototypes of native constructors. Because of that, prototype methods transformed to static methods like in examples above. babel runtime transformer also can't transform them. But with transpilers we can use one more trick - bind operator and virtual methods. Special for that, available /virtual/ entry points. Example:
import fill from 'core-js/library/fn/array/virtual/fill';
import findIndex from 'core-js/library/fn/array/virtual/find-index';
Array(10)::fill(0).map((a, b) => b * b)::findIndex(it => it && !(it % 8)); // => 4
// or
import {fill, findIndex} from 'core-js/library/fn/array/virtual';
Array(10)::fill(0).map((a, b) => b * b)::findIndex(it => it && !(it % 8)); // => 4
Custom build (from the command-line)
npm i core-js && cd node_modules/core-js && npm i
npm run grunt build:core.dict,es6 -- --blacklist=es6.promise,es6.math --library=on --path=custom uglifyWhere core.dict and es6 are modules (namespaces) names, which will be added to the build, es6.promise and es6.math are modules (namespaces) names, which will be excluded from the build, --library=on is flag for build without global namespace pollution and custom is target file name.
Available namespaces: for example, es6.array contains ES6 Array features, es6 contains all modules whose names start with es6.
Custom build (from external scripts)
core-js-builder package exports a function that takes the same parameters as the build target from the previous section. This will conditionally include or exclude certain parts of core-js:
require('core-js-builder')({
modules: ['es6', 'core.dict'], // modules / namespaces
blacklist: ['es6.reflect'], // blacklist of modules / namespaces, by default - empty list
library: false, // flag for build without global namespace pollution, by default - false
umd: true // use UMD wrapper for export `core` object, by default - true
}).then(code => {
// ...
}).catch(error => {
// ...
});Supported engines
Tested in:
- Chrome 26+
- Firefox 4+
- Safari 5+
- Opera 12+
- Internet Explorer 6+ (sure, IE8- with ES3 limitations)
- Edge
- Android Browser 2.3+
- iOS Safari 5.1+
- PhantomJS 1.9 / 2.1
- NodeJS 0.8+
...and it doesn't mean core-js will not work in other engines, they just have not been tested.
Features:
core-js(/library) <- all features
core-js(/library)/shim <- only polyfillsECMAScript 5
All features moved to the es6 namespace, here just a list of features:
Object
.create(proto | null, descriptors?) -> object
.getPrototypeOf(object) -> proto | null
.defineProperty(target, key, desc) -> target, cap for ie8-
.defineProperties(target, descriptors) -> target, cap for ie8-
.getOwnPropertyDescriptor(object, key) -> desc
.getOwnPropertyNames(object) -> array
.keys(object) -> array
.seal(object) -> object, cap for ie8-
.freeze(object) -> object, cap for ie8-
.preventExtensions(object) -> object, cap for ie8-
.isSealed(object) -> bool, cap for ie8-
.isFrozen(object) -> bool, cap for ie8-
.isExtensible(object) -> bool, cap for ie8-
Array
.isArray(var) -> bool
#slice(start?, end?) -> array, fix for ie7-
#join(string = ',') -> string, fix for ie7-
#indexOf(var, from?) -> int
#lastIndexOf(var, from?) -> int
#every(fn(val, index, @), that) -> bool
#some(fn(val, index, @), that) -> bool
#forEach(fn(val, index, @), that) -> void
#map(fn(val, index, @), that) -> array
#filter(fn(val, index, @), that) -> array
#reduce(fn(memo, val, index, @), memo?) -> var
#reduceRight(fn(memo, val, index, @), memo?) -> var
#sort(fn?) -> @, fixes for some engines
Function
#bind(object, ...args) -> boundFn(...args)
String
#split(separator, limit) -> array
#trim() -> str
RegExp
#toString() -> str
Number
#toFixed(digits) -> string
#toPrecision(precision) -> string
parseInt(str, radix) -> int
parseFloat(str) -> num
Date
.now() -> int
#toISOString() -> string
#toJSON() -> stringcore-js(/library)/es5ECMAScript 6
core-js(/library)/es6ECMAScript 6: Object
Modules es6.object.assign, es6.object.is, es6.object.set-prototype-of and es6.object.to-string.
In ES6 most Object static methods should work with primitives. Modules es6.object.freeze, es6.object.seal, es6.object.prevent-extensions, es6.object.is-frozen, es6.object.is-sealed, es6.object.is-extensible, es6.object.get-own-property-descriptor, es6.object.get-prototype-of, es6.object.keys and es6.object.get-own-property-names.
Just ES5 features: es6.object.create, es6.object.define-property and es6.object.define-properties.
Object
.assign(target, ...src) -> target
.is(a, b) -> bool
.setPrototypeOf(target, proto | null) -> target (required __proto__ - IE11+)
.create(object | null, descriptors?) -> object
.getPrototypeOf(var) -> object | null
.defineProperty(object, key, desc) -> target
.defineProperties(object, descriptors) -> target
.getOwnPropertyDescriptor(var, key) -> desc | undefined
.keys(var) -> array
.getOwnPropertyNames(var) -> array
.freeze(var) -> var
.seal(var) -> var
.preventExtensions(var) -> var
.isFrozen(var) -> bool
.isSealed(var) -> bool
.isExtensible(var) -> bool
#toString() -> string, ES6 fix: @@toStringTag supportcore-js(/library)/es6/object
core-js(/library)/fn/object/assign
core-js(/library)/fn/object/is
core-js(/library)/fn/object/set-prototype-of
core-js(/library)/fn/object/get-prototype-of
core-js(/library)/fn/object/create
core-js(/library)/fn/object/define-property
core-js(/library)/fn/object/define-properties
core-js(/library)/fn/object/get-own-property-descriptor
core-js(/library)/fn/object/keys
core-js(/library)/fn/object/get-own-property-names
core-js(/library)/fn/object/freeze
core-js(/library)/fn/object/seal
core-js(/library)/fn/object/prevent-extensions
core-js(/library)/fn/object/is-frozen
core-js(/library)/fn/object/is-sealed
core-js(/library)/fn/object/is-extensible
core-js/fn/object/to-stringvar foo = {q: 1, w: 2}
, bar = {e: 3, r: 4}
, baz = {t: 5, y: 6};
Object.assign(foo, bar, baz); // => foo = {q: 1, w: 2, e: 3, r: 4, t: 5, y: 6}
Object.is(NaN, NaN); // => true
Object.is(0, -0); // => false
Object.is(42, 42); // => true
Object.is(42, '42'); // => false
function Parent(){}
function Child(){}
Object.setPrototypeOf(Child.prototype, Parent.prototype);
new Child instanceof Child; // => true
new Child instanceof Parent; // => true
var O = {};
O[Symbol.toStringTag] = 'Foo';
'' + O; // => '[object Foo]'
Object.keys('qwe'); // => ['0', '1', '2']
Object.getPrototypeOf('qwe') === String.prototype; // => trueECMAScript 6: Function
Modules es6.function.name, es6.function.has-instance. Just ES5: es6.function.bind.
Function
#bind(object, ...args) -> boundFn(...args)
#name -> string (IE9+)
#@@hasInstance(var) -> boolcore-js/es6/function
core-js/fn/function/name
core-js/fn/function/has-instance
core-js/fn/function/bind
core-js/fn/function/virtual/bind(function foo(){}).name // => 'foo'
console.log.bind(console, 42)(43); // => 42 43ECMAScript 6: Array
Modules es6.array.from, es6.array.of, es6.array.copy-within, es6.array.fill, es6.array.find, es6.array.find-index, es6.array.iterator. ES5 features with fixes: es6.array.is-array, es6.array.slice, es6.array.join, es6.array.index-of, es6.array.last-index-of, es6.array.every, es6.array.some, es6.array.for-each, es6.array.map, es6.array.filter, es6.array.reduce, es6.array.reduce-right, es6.array.sort.
Array
.from(iterable | array-like, mapFn(val, index)?, that) -> array
.of(...args) -> array
.isArray(var) -> bool
#copyWithin(target = 0, start = 0, end = @length) -> @
#fill(val, start = 0, end = @length) -> @
#find(fn(val, index, @), that) -> val
#findIndex(fn(val, index, @), that) -> index | -1
#values() -> iterator
#keys() -> iterator
#entries() -> iterator
#join(string = ',') -> string, fix for ie7-
#slice(start?, end?) -> array, fix for ie7-
#indexOf(var, from?) -> index | -1
#lastIndexOf(var, from?) -> index | -1
#every(fn(val, index, @), that) -> bool
#some(fn(val, index, @), that) -> bool
#forEach(fn(val, index, @), that) -> void
#map(fn(val, index, @), that) -> array
#filter(fn(val, index, @), that) -> array
#reduce(fn(memo, val, index, @), memo?) -> var
#reduceRight(fn(memo, val, index, @), memo?) -> var
#sort(fn?) -> @, invalid arguments fix
#@@iterator() -> iterator (values)
#@@unscopables -> object (cap)
Arguments
#@@iterator() -> iterator (values, available only in core-js methods)core-js(/library)/es6/array
core-js(/library)/fn/array/from
core-js(/library)/fn/array/of
core-js(/library)/fn/array/is-array
core-js(/library)/fn/array/iterator
core-js(/library)/fn/array/copy-within
core-js(/library)/fn/array/fill
core-js(/library)/fn/array/find
core-js(/library)/fn/array/find-index
core-js(/library)/fn/array/values
core-js(/library)/fn/array/keys
core-js(/library)/fn/array/entries
core-js(/library)/fn/array/slice
core-js(/library)/fn/array/join
core-js(/library)/fn/array/index-of
core-js(/library)/fn/array/last-index-of
core-js(/library)/fn/array/every
core-js(/library)/fn/array/some
core-js(/library)/fn/array/for-each
core-js(/library)/fn/array/map
core-js(/library)/fn/array/filter
core-js(/library)/fn/array/reduce
core-js(/library)/fn/array/reduce-right
core-js(/library)/fn/array/sort
core-js(/library)/fn/array/virtual/iterator
core-js(/library)/fn/array/virtual/copy-within
core-js(/library)/fn/array/virtual/fill
core-js(/library)/fn/array/virtual/find
core-js(/library)/fn/array/virtual/find-index
core-js(/library)/fn/array/virtual/values
core-js(/library)/fn/array/virtual/keys
core-js(/library)/fn/array/virtual/entries
core-js(/library)/fn/array/virtual/slice
core-js(/library)/fn/array/virtual/join
core-js(/library)/fn/array/virtual/index-of
core-js(/library)/fn/array/virtual/last-index-of
core-js(/library)/fn/array/virtual/every
core-js(/library)/fn/array/virtual/some
core-js(/library)/fn/array/virtual/for-each
core-js(/library)/fn/array/virtual/map
core-js(/library)/fn/array/virtual/filter
core-js(/library)/fn/array/virtual/reduce
core-js(/library)/fn/array/virtual/reduce-right
core-js(/library)/fn/array/virtual/sortArray.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
Array.from({0: 1, 1: 2, 2: 3, length: 3}); // => [1, 2, 3]
Array.from('123', Number); // => [1, 2, 3]
Array.from('123', function(it){
return it * it;
}); // => [1, 4, 9]
Array.of(1); // => [1]
Array.of(1, 2, 3); // => [1, 2, 3]
var array = ['a', 'b', 'c'];
for(var val of array)console.log(val); // => 'a', 'b', 'c'
for(var val of array.values())console.log(val); // => 'a', 'b', 'c'
for(var key of array.keys())console.log(key); // => 0, 1, 2
for(var [key, val] of array.entries()){
console.log(key); // => 0, 1, 2
console.log(val); // => 'a', 'b', 'c'
}
function isOdd(val){
return val % 2;
}
[4, 8, 15, 16, 23, 42].find(isOdd); // => 15
[4, 8, 15, 16, 23, 42].findIndex(isOdd); // => 2
[4, 8, 15, 16, 23, 42].find(isNaN); // => undefined
[4, 8, 15, 16, 23, 42].findIndex(isNaN); // => -1
Array(5).fill(42); // => [42, 42, 42, 42, 42]
[1, 2, 3, 4, 5].copyWithin(0, 3); // => [4, 5, 3, 4, 5]ECMAScript 6: String
Modules es6.string.from-code-point, es6.string.raw, es6.string.iterator, es6.string.code-point-at, es6.string.ends-with, es6.string.includes, es6.string.repeat, es6.string.starts-with and es6.string.trim.
Annex B HTML methods. Ugly, but it's also the part of the spec. Modules es6.string.anchor, es6.string.big, es6.string.blink, es6.string.bold, es6.string.fixed, es6.string.fontcolor, es6.string.fontsize, es6.string.italics, es6.string.link, es6.string.small, es6.string.strike, es6.string.sub and es6.string.sup.
String
.fromCodePoint(...codePoints) -> str
.raw({raw}, ...substitutions) -> str
#includes(str, from?) -> bool
#startsWith(str, from?) -> bool
#endsWith(str, from?) -> bool
#repeat(num) -> str
#codePointAt(pos) -> uint
#trim() -> str, ES6 fix
#anchor(name) -> str
#big() -> str
#blink() -> str
#bold() -> str
#fixed() -> str
#fontcolor(color) -> str
#fontsize(size) -> str
#italics() -> str
#link(url) -> str
#small() -> str
#strike() -> str
#sub() -> str
#sup() -> str
#@@iterator() -> iterator (code points)core-js(/library)/es6/string
core-js(/library)/fn/string/from-code-point
core-js(/library)/fn/string/raw
core-js(/library)/fn/string/includes
core-js(/library)/fn/string/starts-with
core-js(/library)/fn/string/ends-with
core-js(/library)/fn/string/repeat
core-js(/library)/fn/string/code-point-at
core-js(/library)/fn/string/trim
core-js(/library)/fn/string/anchor
core-js(/library)/fn/string/big
core-js(/library)/fn/string/blink
core-js(/library)/fn/string/bold
core-js(/library)/fn/string/fixed
core-js(/library)/fn/string/fontcolor
core-js(/library)/fn/string/fontsize
core-js(/library)/fn/string/italics
core-js(/library)/fn/string/link
core-js(/library)/fn/string/small
core-js(/library)/fn/string/strike
core-js(/library)/fn/string/sub
core-js(/library)/fn/string/sup
core-js(/library)/fn/string/iterator
core-js(/library)/fn/string/virtual/includes
core-js(/library)/fn/string/virtual/starts-with
core-js(/library)/fn/string/virtual/ends-with
core-js(/library)/fn/string/virtual/repeat
core-js(/library)/fn/string/virtual/code-point-at
core-js(/library)/fn/string/virtual/trim
core-js(/library)/fn/string/virtual/anchor
core-js(/library)/fn/string/virtual/big
core-js(/library)/fn/string/virtual/blink
core-js(/library)/fn/string/virtual/bold
core-js(/library)/fn/string/virtual/fixed
core-js(/library)/fn/string/virtual/fontcolor
core-js(/library)/fn/string/virtual/fontsize
core-js(/library)/fn/string/virtual/italics
core-js(/library)/fn/string/virtual/link
core-js(/library)/fn/string/virtual/small
core-js(/library)/fn/string/virtual/strike
core-js(/library)/fn/string/virtual/sub
core-js(/library)/fn/string/virtual/sup
core-js(/library)/fn/string/virtual/iterator
for(var val of 'a
