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); // => 42
Without 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); // => 42
- Usage
- Supported engines
- Features
- Missing polyfills
- Changelog
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.
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); // => 2
Available 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.
modules
path 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-js
is extremely modular and uses a lot of very tiny modules, because of that for usage in browsers bundle upcore-js
instead of usage loader for each file, otherwise, you will have hundreds of requests.
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
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 uglify
Where 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
.
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 => {
// ...
});
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.
core-js(/library) <- all features
core-js(/library)/shim <- only polyfills
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() -> string
core-js(/library)/es5
core-js(/library)/es6
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 support
core-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-string
var 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; // => true
Modules es6.function.name
, es6.function.has-instance
. Just ES5: es6.function.bind
.
Function
#bind(object, ...args) -> boundFn(...args)
#name -> string (IE9+)
#@@hasInstance(var) -> bool
core-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 43
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/sort
Array.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]
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 'a๐ ฎทb'){
console.log(val); // => 'a', '๐ ฎท', 'b'
}
'foobarbaz'.includes('bar'); // => true
'foobarbaz'.includes('bar', 4); // => false
'foobarbaz'.startsWith('foo'); // => true
'foobarbaz'.startsWith('bar', 3); // => true
'foobarbaz'.endsWith('baz'); // => true
'foobarbaz'.endsWith('bar', 6); // => true
'string'.repeat(3); // => 'stringstringstring'
'๐ ฎท'.codePointAt(0); // => 134071
String.fromCodePoint(97, 134071, 98); // => 'a๐ ฎทb'
var name = 'Bob';
String.raw`Hi\n${name}!`; // => 'Hi\\nBob!' (ES6 template string syntax)
String.raw({raw: 'test'}, 0, 1, 2); // => 't0e1s2t'
'foo'.bold(); // => '<b>foo</b>'
'bar'.anchor('a"b'); // => '<a name="a"b">bar</a>'
'baz'.link('http://example.com'); // => '<a href="http://example.com">baz</a>'
Modules es6.regexp.constructor
and es6.regexp.flags
.
Support well-known symbols @@match
, @@replace
, @@search
and @@split
, modules es6.regexp.match
, es6.regexp.replace
, es6.regexp.search
and es6.regexp.split
.
[new] RegExp(pattern, flags?) -> regexp, ES6 fix: can alter flags (IE9+)
#flags -> str (IE9+)
#toString() -> str, ES6 fixes
#@@match(str) -> array | null
#@@replace(str, replacer) -> string
#@@search(str) -> index
#@@split(str, limit) -> array
String
#match(tpl) -> var, ES6 fix for support @@match
#replace(tpl, replacer) -> var, ES6 fix for support @@replace
#search(tpl) -> var, ES6 fix for support @@search
#split(tpl, limit) -> var, ES6 fix for support @@split, some fixes for old engines
core-js/es6/regexp
core-js/fn/regexp/constructor
core-js(/library)/fn/regexp/flags
core-js/fn/regexp/to-string
core-js/fn/regexp/match
core-js/fn/regexp/replace
core-js/fn/regexp/search
core-js/fn/regexp/split
RegExp(/./g, 'm'); // => /./m
/foo/.flags; // => ''
/foo/gim.flags; // => 'gim'
'foo'.match({[Symbol.match]: _ => 1}); // => 1
'foo'.replace({[Symbol.replace]: _ => 2}); // => 2
'foo'.search({[Symbol.search]: _ => 3}); // => 3
'foo'.split({[Symbol.split]: _ => 4}); // => 4
RegExp.prototype.toString.call({source: 'foo', flags: 'bar'}); // => '/foo/bar'
Module es6.number.constructor
. Number
constructor support binary and octal literals, example:
Number('0b1010101'); // => 85
Number('0o7654321'); // => 2054353
Modules es6.number.epsilon
, es6.number.is-finite
, es6.number.is-integer
, es6.number.is-nan
, es6.number.is-safe-integer
, es6.number.max-safe-integer
, es6.number.min-safe-integer
, es6.number.parse-float
, es6.number.parse-int
, es6.number.to-fixed
, es6.number.to-precision
, es6.parse-int
, es6.parse-float
.
[new] Number(var) -> number | number object
.isFinite(num) -> bool
.isNaN(num) -> bool
.isInteger(num) -> bool
.isSafeInteger(num) -> bool
.parseFloat(str) -> num
.parseInt(str) -> int
.EPSILON -> num
.MAX_SAFE_INTEGER -> int
.MIN_SAFE_INTEGER -> int
#toFixed(digits) -> string, fixes
#toPrecision(precision) -> string, fixes
parseFloat(str) -> num, fixes
parseInt(str) -> int, fixes
core-js(/library)/es6/number
core-js/es6/number/constructor
core-js(/library)/fn/number/is-finite
core-js(/library)/fn/number/is-nan
core-js(/library)/fn/number/is-integer
core-js(/library)/fn/number/is-safe-integer
core-js(/library)/fn/number/parse-float
core-js(/library)/fn/number/parse-int
core-js(/library)/fn/number/epsilon
core-js(/library)/fn/number/max-safe-integer
core-js(/library)/fn/number/min-safe-integer
core-js(/library)/fn/number/to-fixed
core-js(/library)/fn/number/to-precision
core-js(/library)/fn/parse-float
core-js(/library)/fn/parse-int
Modules es6.math.acosh
, es6.math.asinh
, es6.math.atanh
, es6.math.cbrt
, es6.math.clz32
, es6.math.cosh
, es6.math.expm1
, es6.math.fround
, es6.math.hypot
, es6.math.imul
, es6.math.log10
, es6.math.log1p
, es6.math.log2
, es6.math.sign
, es6.math.sinh
, es6.math.tanh
, es6.math.trunc
.
Math
.acosh(num) -> num
.asinh(num) -> num
.atanh(num) -> num
.cbrt(num) -> num
.clz32(num) -> uint
.cosh(num) -> num
.expm1(num) -> num
.fround(num) -> num
.hypot(...args) -> num
.imul(num, num) -> int
.log1p(num) -> num
.log10(num) -> num
.log2(num) -> num
.sign(num) -> 1 | -1 | 0 | -0 | NaN
.sinh(num) -> num
.tanh(num) -> num
.trunc(num) -> num
core-js(/library)/es6/math
core-js(/library)/fn/math/acosh
core-js(/library)/fn/math/asinh
core-js(/library)/fn/math/atanh
core-js(/library)/fn/math/cbrt
core-js(/library)/fn/math/clz32
core-js(/library)/fn/math/cosh
core-js(/library)/fn/math/expm1
core-js(/library)/fn/math/fround
core-js(/library)/fn/math/hypot
core-js(/library)/fn/math/imul
core-js(/library)/fn/math/log1p
core-js(/library)/fn/math/log10
core-js(/library)/fn/math/log2
core-js(/library)/fn/math/sign
core-js(/library)/fn/math/sinh
core-js(/library)/fn/math/tanh
core-js(/library)/fn/math/trunc
Modules es6.date.to-string
, ES5 features with fixes: es6.date.now
, es6.date.to-iso-string
, es6.date.to-json
and es6.date.to-primitive
.
Date
.now() -> int
#toISOString() -> string
#toJSON() -> string
#toString() -> string
#@@toPrimitive(hint) -> primitive
core-js/es6/date
core-js/fn/date/to-string
core-js(/library)/fn/date/now
core-js(/library)/fn/date/to-iso-string
core-js(/library)/fn/date/to-json
core-js(/library)/fn/date/to-primitive
new Date(NaN).toString(); // => 'Invalid Date'
Module es6.promise
.
new Promise(executor(resolve(var), reject(var))) -> promise
#then(resolved(var), rejected(var)) -> promise
#catch(rejected(var)) -> promise
.resolve(promise | var) -> promise
.reject(var) -> promise
.all(iterable) -> promise
.race(iterable) -> promise
core-js(/library)/es6/promise
core-js(/library)/fn/promise
Basic example:
function sleepRandom(time){
return new Promise(function(resolve, reject){
setTimeout(resolve, time * 1e3, 0 | Math.random() * 1e3);
});
}
console.log('Run'); // => Run
sleepRandom(5).then(function(result){
console.log(result); // => 869, after 5 sec.
return sleepRandom(10);
}).then(function(result){
console.log(result); // => 202, after 10 sec.
}).then(function(){
console.log('immediately after'); // => immediately after
throw Error('Irror!');
}).then(function(){
console.log('will not be displayed');
}).catch(x => console.log(x)); // => => Error: Irror!
Promise.resolve
and Promise.reject
example:
Promise.resolve(42).then(x => console.log(x)); // => 42
Promise.reject(42).catch(x => console.log(x)); // => 42
Promise.resolve($.getJSON('/data.json')); // => ES6 promise
Promise.all
example:
Promise.all([
'foo',
sleepRandom(5),
sleepRandom(15),
sleepRandom(10) // after 15 sec:
]).then(x => console.log(x)); // => ['foo', 956, 85, 382]
Promise.race
example:
function timeLimit(promise, time){
return Promise.race([promise, new Promise(function(resolve, reject){
setTimeout(reject, time * 1e3, Error('Await > ' + time + ' sec'));
})]);
}
timeLimit(sleepRandom(5), 10).then(x => console.log(x)); // => 853, after 5 sec.
timeLimit(sleepRandom(15), 10).catch(x => console.log(x)); // Error: Await > 10 sec
ECMAScript 7 async functions example:
var delay = time => new Promise(resolve => setTimeout(resolve, time))
async function sleepRandom(time){
await delay(time * 1e3);
return 0 | Math.random() * 1e3;
};
async function sleepError(time, msg){
await delay(time * 1e3);
throw Error(msg);
};
(async () => {
try {
console.log('Run'); // => Run
console.log(await sleepRandom(5)); // => 936, after 5 sec.
var [a, b, c] = await Promise.all([
sleepRandom(5),
sleepRandom(15),
sleepRandom(10)
]);
console.log(a, b, c); // => 210 445 71, after 15 sec.
await sleepError(5, 'Irror!');
console.log('Will not be displayed');
} catch(e){
console.log(e); // => Error: 'Irror!', after 5 sec.
}
})();
In Node.js, like in native implementation, available events unhandledRejection
and rejectionHandled
:
process.on('unhandledRejection', (reason, promise) => console.log('unhandled', reason, promise));
process.on('rejectionHandled', (promise) => console.log('handled', promise));
var p = Promise.reject(42);
// unhandled 42 [object Promise]
setTimeout(() => p.catch(_ => _), 1e3);
// handled [object Promise]
In a browser on rejection, by default, you will see notify in the console, or you can add a custom handler and a handler on handling unhandled, example:
window.onunhandledrejection = e => console.log('unhandled', e.reason, e.promise);
window.onrejectionhandled = e => console.log('handled', e.reason, e.promise);
var p = Promise.reject(42);
// unhandled 42 [object Promise]
setTimeout(() => p.catch(_ => _), 1e3);
// handled 42 [object Promise]
Module es6.symbol
.
Symbol(description?) -> symbol
.hasInstance -> @@hasInstance
.isConcatSpreadable -> @@isConcatSpreadable
.iterator -> @@iterator
.match -> @@match
.replace -> @@replace
.search -> @@search
.species -> @@species
.split -> @@split
.toPrimitive -> @@toPrimitive
.toStringTag -> @@toStringTag
.unscopables -> @@unscopables
.for(key) -> symbol
.keyFor(symbol) -> key
.useSimple() -> void
.useSetter() -> void
Object
.getOwnPropertySymbols(object) -> array
Also wrapped some methods for correct work with Symbol
polyfill.
Object
.create(proto | null, descriptors?) -> object
.defineProperty(target, key, desc) -> target
.defineProperties(target, descriptors) -> target
.getOwnPropertyDescriptor(var, key) -> desc | undefined
.getOwnPropertyNames(var) -> array
#propertyIsEnumerable(key) -> bool
JSON
.stringify(target, replacer?, space?) -> string | undefined
core-js(/library)/es6/symbol
core-js(/library)/fn/symbol
core-js(/library)/fn/symbol/has-instance
core-js(/library)/fn/symbol/is-concat-spreadable
core-js(/library)/fn/symbol/iterator
core-js(/library)/fn/symbol/match
core-js(/library)/fn/symbol/replace
core-js(/library)/fn/symbol/search
core-js(/library)/fn/symbol/species
core-js(/library)/fn/symbol/split
core-js(/library)/fn/symbol/to-primitive
core-js(/library)/fn/symbol/to-string-tag
core-js(/library)/fn/symbol/unscopables
core-js(/library)/fn/symbol/for
core-js(/library)/fn/symbol/key-for
var Person = (function(){
var NAME = Symbol('name');
function Person(name){
this[NAME] = name;
}
Person.prototype.getName = function(){
return this[NAME];
};
return Person;
})();
var person = new Person('Vasya');
console.log(person.getName()); // => 'Vasya'
console.log(person['name']); // => undefined
console.log(person[Symbol('name')]); // => undefined, symbols are uniq
for(var key in person)console.log(key); // => only 'getName', symbols are not enumerable
Symbol.for
& Symbol.keyFor
example:
var symbol = Symbol.for('key');
symbol === Symbol.for('key'); // true
Symbol.keyFor(symbol); // 'key'
Example with methods for getting own object keys:
var O = {a: 1};
Object.defineProperty(O, 'b', {value: 2});
O[Symbol('c')] = 3;
Object.keys(O); // => ['a']
Object.getOwnPropertyNames(O); // => ['a', 'b']
Object.getOwnPropertySymbols(O); // => [Symbol(c)]
Reflect.ownKeys(O); // => ['a', 'b', Symbol(c)]
- We can't add new primitive type,
Symbol
returns object. Symbol.for
andSymbol.keyFor
can't be shimmed cross-realm.- By default, to hide the keys,
Symbol
polyfill defines setter inObject.prototype
. For this reason, uncontrolled creation of symbols can cause memory leak and thein
operator is not working correctly withSymbol
polyfill:Symbol() in {} // => true
.
You can disable defining setters in Object.prototype
. Example:
Symbol.useSimple();
var s1 = Symbol('s1')
, o1 = {};
o1[s1] = true;
for(var key in o1)console.log(key); // => 'Symbol(s1)_t.qamkg9f3q', w/o native Symbol
Symbol.useSetter();
var s2 = Symbol('s2')
, o2 = {};
o2[s2] = true;
for(var key in o2)console.log(key); // nothing
- Currently,
core-js
not adds setters toObject.prototype
for well-known symbols for correct work something likeSymbol.iterator in foo
. It can cause problems with their enumerability. - Some problems possible with environment exotic objects (for example, IE
localStorage
).
core-js
uses native collections in most case, just fixes methods / constructor, if it's required, and in old environment uses fast polyfill (O(1) lookup).
Module es6.map
.
new Map(iterable (entries) ?) -> map
#clear() -> void
#delete(key) -> bool
#forEach(fn(val, key, @), that) -> void
#get(key) -> val
#has(key) -> bool
#set(key, val) -> @
#size -> uint
#values() -> iterator
#keys() -> iterator
#entries() -> iterator
#@@iterator() -> iterator (entries)
core-js(/library)/es6/map
core-js(/library)/fn/map
var a = [1];
var map = new Map([['a', 1], [42, 2]]);
map.set(a, 3).set(true, 4);
console.log(map.size); // => 4
console.log(map.has(a)); // => true
console.log(map.has([1])); // => false
console.log(map.get(a)); // => 3
map.forEach(function(val, key){
console.log(val); // => 1, 2, 3, 4
console.log(key); // => 'a', 42, [1], true
});
map.delete(a);
console.log(map.size); // => 3
console.log(map.get(a)); // => undefined
console.log(Array.from(map)); // => [['a', 1], [42, 2], [true, 4]]
var map = new Map([['a', 1], ['b', 2], ['c', 3]]);
for(var [key, val] of map){
console.log(key); // => 'a', 'b', 'c'
console.log(val); // => 1, 2, 3
}
for(var val of map.values())console.log(val); // => 1, 2, 3
for(var key of map.keys())console.log(key); // => 'a', 'b', 'c'
for(var [key, val] of map.entries()){
console.log(key); // => 'a', 'b', 'c'
console.log(val); // => 1, 2, 3
}
Module es6.set
.
new Set(iterable?) -> set
#add(key) -> @
#clear() -> void
#delete(key) -> bool
#forEach(fn(el, el, @), that) -> void
#has(key) -> bool
#size -> uint
#values() -> iterator
#keys() -> iterator
#entries() -> iterator
#@@iterator() -> iterator (values)
core-js(/library)/es6/set
core-js(/library)/fn/set
var set = new Set(['a', 'b', 'a', 'c']);
set.add('d').add('b').add('e');
console.log(set.size); // => 5
console.log(set.has('b')); // => true
set.forEach(function(it){
console.log(it); // => 'a', 'b', 'c', 'd', 'e'
});
set.delete('b');
console.log(set.size); // => 4
console.log(set.has('b')); // => false
console.log(Array.from(set)); // => ['a', 'c', 'd', 'e']
var set = new Set([1, 2, 3, 2, 1]);
for(var val of set)console.log(val); // => 1, 2, 3
for(var val of set.values())console.log(val); // => 1, 2, 3
for(var key of set.keys())console.log(key); // => 1, 2, 3
for(var [key, val] of set.entries()){
console.log(key); // => 1, 2, 3
console.log(val); // => 1, 2, 3
}
Module es6.weak-map
.
new WeakMap(iterable (entries) ?) -> weakmap
#delete(key) -> bool
#get(key) -> val
#has(key) -> bool
#set(key, val) -> @
core-js(/library)/es6/weak-map
core-js(/library)/fn/weak-map
var a = [1]
, b = [2]
, c = [3];
var wmap = new WeakMap([[a, 1], [b, 2]]);
wmap.set(c, 3).set(b, 4);
console.log(wmap.has(a)); // => true
console.log(wmap.has([1])); // => false
console.log(wmap.get(a)); // => 1
wmap.delete(a);
console.log(wmap.get(a)); // => undefined
// Private properties store:
var Person = (function(){
var names = new WeakMap;
function Person(name){
names.set(this, name);
}
Person.prototype.getName = function(){
return names.get(this);
};
return Person;
})();
var person = new Person('Vasya');
console.log(person.getName()); // => 'Vasya'
for(var key in person)console.log(key); // => only 'getName'
Module es6.weak-set
.
new WeakSet(iterable?) -> weakset
#add(key) -> @
#delete(key) -> bool
#has(key) -> bool
core-js(/library)/es6/weak-set
core-js(/library)/fn/weak-set
var a = [1]
, b = [2]
, c = [3];
var wset = new WeakSet([a, b, a]);
wset.add(c).add(b).add(c);
console.log(wset.has(b)); // => true
console.log(wset.has([2])); // => false
wset.delete(b);
console.log(wset.has(b)); // => false
- Weak-collections polyfill stores values as hidden properties of keys. It works correct and not leak in most cases. However, it is desirable to store a collection longer than its keys.
Implementations and fixes ArrayBuffer
, DataView
, typed arrays constructors, static and prototype methods. Typed Arrays work only in environments with support descriptors (IE9+), ArrayBuffer
and DataView
should work anywhere.
Modules es6.typed.array-buffer
, es6.typed.data-view
, es6.typed.int8-array
, es6.typed.uint8-array
, es6.typed.uint8-clamped-array
, es6.typed.int16-array
, es6.typed.uint16-array
, es6.typed.int32-array
, es6.typed.uint32-array
, es6.typed.float32-array
and es6.typed.float64-array
.
new ArrayBuffer(length) -> buffer
.isView(var) -> bool
#slice(start = 0, end = @length) -> buffer
#byteLength -> uint
new DataView(buffer, byteOffset = 0, byteLength = buffer.byteLength - byteOffset) -> view
#getInt8(offset) -> int8
#getUint8(offset) -> uint8
#getInt16(offset, littleEndian = false) -> int16
#getUint16(offset, littleEndian = false) -> uint16
#getInt32(offset, littleEndian = false) -> int32
#getUint32(offset, littleEndian = false) -> uint32
#getFloat32(offset, littleEndian = false) -> float32
#getFloat64(offset, littleEndian = false) -> float64
#setInt8(offset, value) -> void
#setUint8(offset, value) -> void
#setInt16(offset, value, littleEndian = false) -> void
#setUint16(offset, value, littleEndian = false) -> void
#setInt32(offset, value, littleEndian = false) -> void
#setUint32(offset, value, littleEndian = false) -> void
#setFloat32(offset, value, littleEndian = false) -> void
#setFloat64(offset, value, littleEndian = false) -> void
#buffer -> buffer
#byteLength -> uint
#byteOffset -> uint
{
Int8Array,
Uint8Array,
Uint8ClampedArray,
Int16Array,
Uint16Array,
Int32Array,
Uint32Array,
Float32Array,
Float64Array
}
new %TypedArray%(length) -> typed
new %TypedArray%(typed) -> typed
new %TypedArray%(arrayLike) -> typed
new %TypedArray%(iterable) -> typed
new %TypedArray%(buffer, byteOffset = 0, length = (buffer.byteLength - byteOffset) / @BYTES_PER_ELEMENT) -> typed
.BYTES_PER_ELEMENT -> uint
.from(arrayLike | iterable, mapFn(val, index)?, that) -> typed
.of(...args) -> typed
#BYTES_PER_ELEMENT -> uint
#copyWithin(target = 0, start = 0, end = @length) -> @
#every(fn(val, index, @), that) -> bool
#fill(val, start = 0, end = @length) -> @
#filter(fn(val, index, @), that) -> typed
#find(fn(val, index, @), that) -> val
#findIndex(fn(val, index, @), that) -> index
#forEach(fn(val, index, @), that) -> void
#indexOf(var, from?) -> int
#includes(var, from?) -> bool
#join(string = ',') -> string
#lastIndexOf(var, from?) -> int
#map(fn(val, index, @), that) -> typed
#reduce(fn(memo, val, index, @), memo?) -> var
#reduceRight(fn(memo, val, index, @), memo?) -> var
#reverse() -> @
#set(arrayLike, offset = 0) -> void
#slice(start = 0, end = @length) -> typed
#some(fn(val, index, @), that) -> bool
#sort(fn(a, b)?) -> @
#subarray(start = 0, end = @length) -> typed
#toString() -> string
#toLocaleString() -> string
#values() -> iterator
#keys() -> iterator
#entries() -> iterator
#@@iterator() -> iterator (values)
#buffer -> buffer
#byteLength -> uint
#byteOffset -> uint
#length -> uint
core-js(/library)/es6/typed
core-js(/library)/fn/typed
core-js(/library)/fn/typed/array-buffer
core-js(/library)/fn/typed/data-view
core-js(/library)/fn/typed/int8-array
core-js(/library)/fn/typed/uint8-array
core-js(/library)/fn/typed/uint8-clamped-array
core-js(/library)/fn/typed/int16-array
core-js(/library)/fn/typed/uint16-array
core-js(/library)/fn/typed/int32-array
core-js(/library)/fn/typed/uint32-array
core-js(/library)/fn/typed/float32-array
core-js(/library)/fn/typed/float64-array
new Int32Array(4); // => [0, 0, 0, 0]
new Uint8ClampedArray([1, 2, 3, 666]); // => [1, 2, 3, 255]
new Float32Array(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
var buffer = new ArrayBuffer(8);
var view = new DataView(buffer);
view.setFloat64(0, 123.456, true);
new Uint8Array(buffer.slice(4)); // => [47, 221, 94, 64]
Int8Array.of(1, 1.5, 5.7, 745); // => [1, 1, 5, -23]
Uint8Array.from([1, 1.5, 5.7, 745]); // => [1, 1, 5, 233]
var typed = new Uint8Array([1, 2, 3]);
var a = typed.slice(1); // => [2, 3]
typed.buffer === a.buffer; // => false
var b = typed.subarray(1); // => [2, 3]
typed.buffer === b.buffer; // => true
typed.filter(it => it % 2); // => [1, 3]
typed.map(it => it * 1.5); // => [1, 3, 4]
for(var val of typed)console.log(val); // => 1, 2, 3
for(var val of typed.values())console.log(val); // => 1, 2, 3
for(var key of typed.keys())console.log(key); // => 0, 1, 2
for(var [key, val] of typed.entries()){
console.log(key); // => 0, 1, 2
console.log(val); // => 1, 2, 3
}
- Typed Arrays polyfills works completely how should work by the spec, but because of internal use getter / setters on each instance, is slow and consumes significant memory. However, typed arrays polyfills required mainly for IE9 (and for
Uint8ClampedArray
in IE10 and early IE11), all modern engines have native typed arrays and requires only constructors fixes and methods. - The current version hasn't special entry points for methods, they can be added only with constructors. It can be added in the future.
- In the
library
version we can't pollute native prototypes, so prototype methods available as constructors static.
Modules es6.reflect.apply
, es6.reflect.construct
, es6.reflect.define-property
, es6.reflect.delete-property
, es6.reflect.enumerate
, es6.reflect.get
, es6.reflect.get-own-property-descriptor
, es6.reflect.get-prototype-of
, es6.reflect.has
, es6.reflect.is-extensible
, es6.reflect.own-keys
, es6.reflect.prevent-extensions
, es6.reflect.set
, es6.reflect.set-prototype-of
.
Reflect
.apply(target, thisArgument, argumentsList) -> var
.construct(target, argumentsList, newTarget?) -> object
.defineProperty(target, propertyKey, attributes) -> bool
.deleteProperty(target, propertyKey) -> bool
.enumerate(target) -> iterator (deprecated and will be removed from the next major release)
.get(target, propertyKey, receiver?) -> var
.getOwnPropertyDescriptor(target, propertyKey) -> desc
.getPrototypeOf(target) -> object | null
.has(target, propertyKey) -> bool
.isExtensible(target) -> bool
.ownKeys(target) -> array
.preventExtensions(target) -> bool
.set(target, propertyKey, V, receiver?) -> bool
.setPrototypeOf(target, proto) -> bool (required __proto__ - IE11+)
core-js(/library)/es6/reflect
core-js(/library)/fn/reflect
core-js(/library)/fn/reflect/apply
core-js(/library)/fn/reflect/construct
core-js(/library)/fn/reflect/define-property
core-js(/library)/fn/reflect/delete-property
core-js(/library)/fn/reflect/enumerate (deprecated and will be removed from the next major release)
core-js(/library)/fn/reflect/get
core-js(/library)/fn/reflect/get-own-property-descriptor
core-js(/library)/fn/reflect/get-prototype-of
core-js(/library)/fn/reflect/has
core-js(/library)/fn/reflect/is-extensible
core-js(/library)/fn/reflect/own-keys
core-js(/library)/fn/reflect/prevent-extensions
core-js(/library)/fn/reflect/set
core-js(/library)/fn/reflect/set-prototype-of
var O = {a: 1};
Object.defineProperty(O, 'b', {value: 2});
O[Symbol('c')] = 3;
Reflect.ownKeys(O); // => ['a', 'b', Symbol(c)]
function C(a, b){
this.c = a + b;
}
var instance = Reflect.construct(C, [20, 22]);
instance.c; // => 42
core-js(/library)/es7
core-js(/library)/es7/array
core-js(/library)/es7/string
core-js(/library)/es7/map
core-js(/library)/es7/set
core-js(/library)/es7/math
core-js(/library)/es7/system
core-js(/library)/es7/error
core-js(/library)/es7/reflect
core-js/stage/4
entry point contains only stage 4 proposals, core-js/stage/3
- stage 3 and stage 4, etc.
{Array, %TypedArray%}#includes
proposal - modulees7.array.includes
,%TypedArray%
version in modules from this section.Object#__(define|lookup)[GS]etter__
, annex B ES2017, but we haven't special namespace for that - moduleses7.object.define-setter
,es7.object.define-getter
,es7.object.lookup-setter
andes7.object.lookup-getter
.
core-js(/library)/stage/4
core-js(/library)/fn/array/includes
core-js(/library)/fn/object/define-getter
core-js(/library)/fn/object/define-setter
core-js(/library)/fn/object/lookup-getter
core-js(/library)/fn/object/lookup-setter
Object.values
,Object.entries
proposal - moduleses7.object.values
,es7.object.entries
Object.getOwnPropertyDescriptors
proposal - modulees7.object.get-own-property-descriptors
String#padStart
,String#padEnd
proposal - moduleses7.string.pad-left
,es7.string.pad-right
core-js(/library)/stage/3
core-js(/library)/fn/object/values
core-js(/library)/fn/object/entries
core-js(/library)/fn/string/pad-start
core-js(/library)/fn/string/pad-end
core-js(/library)/fn/string/virtual/pad-start
core-js(/library)/fn/string/virtual/pad-end
None.
core-js(/library)/stage/2
String#trimLeft
,String#trimRight
/String#trimStart
,String#trimEnd
proposal - moduleses7.string.trim-left
,es7.string.trim-right
String#matchAll
proposal - modulees7.string.match-all
System.global
proposal - modulees7.system.global
core-js(/library)/stage/1
core-js(/library)/fn/string/trim-start
core-js(/library)/fn/string/trim-end
core-js(/library)/fn/string/trim-left
core-js(/library)/fn/string/trim-right
core-js(/library)/fn/string/match-all
core-js(/library)/fn/string/virtual/trim-start
core-js(/library)/fn/string/virtual/trim-end
core-js(/library)/fn/string/virtual/trim-left
core-js(/library)/fn/string/virtual/trim-right
core-js(/library)/fn/string/virtual/match-all
core-js(/library)/fn/system/global
String#at
proposal - modulees7.string.at
Map#toJSON
,Set#toJSON
proposal - moduleses7.map.to-json
,es7.set.to-json
Error.isError
proposal - modulees7.error.is-error
Math.{iaddh, isubh, imulh, umulh}
proposal - moduleses7.math.iaddh
,es7.math.isubh
,es7.math.imulh
andes7.math.umulh
.
core-js(/library)/stage/0
core-js(/library)/fn/string/at
core-js(/library)/fn/string/virtual/at
core-js(/library)/fn/object/get-own-property-descriptors
core-js(/library)/fn/map
core-js(/library)/fn/set
core-js(/library)/fn/error/is-error
core-js(/library)/fn/math/iaddh
core-js(/library)/fn/math/isubh
core-js(/library)/fn/math/imulh
core-js(/library)/fn/math/umulh
Reflect
metadata proposal - moduleses7.reflect.define-metadata
,es7.reflect.delete-metadata
,es7.reflect.get-metadata
,es7.reflect.get-metadata-keys
,es7.reflect.get-own-metadata
,es7.reflect.get-own-metadata-keys
,es7.reflect.has-metadata
,es7.reflect.has-own-metadata
andes7.reflect.metadata
.
core-js(/library)/stage/pre
core-js(/library)/fn/reflect/define-metadata
core-js(/library)/fn/reflect/delete-metadata
core-js(/library)/fn/reflect/get-metadata
core-js(/library)/fn/reflect/get-metadata-keys
core-js(/library)/fn/reflect/get-own-metadata
core-js(/library)/fn/reflect/get-own-metadata-keys
core-js(/library)/fn/reflect/has-metadata
core-js(/library)/fn/reflect/has-own-metadata
core-js(/library)/fn/reflect/metadata
Array
#includes(var, from?) -> bool
String
#at(index) -> string
#padStart(length, fillStr = ' ') -> string
#padEnd(length, fillStr = ' ') -> string
#trimLeft() -> string
#trimRight() -> string
#trimStart() -> string
#trimEnd() -> string
#marchAll(regexp) -> iterator
Object
.values(object) -> array
.entries(object) -> array
.getOwnPropertyDescriptors(object) -> object
#__defineSetter__(key, fn) -> void
#__defineGetter__(key, fn) -> void
#__lookupSetter__(key) -> fn | void
#__lookupGetter__(key) -> fn | void
RegExp
.escape(str) -> str
Map
#toJSON() -> array
Set
#toJSON() -> array
System
.global -> object
Error
.isError(it) -> bool
Math
.iaddh(lo0, hi0, lo1, hi1) -> int32
.isubh(lo0, hi0, lo1, hi1) -> int32
.imulh(a, b) -> int32
.umulh(a, b) -> uint32
Reflect
.defineMetadata(metadataKey, metadataValue, target, propertyKey?) -> void
.getMetadata(metadataKey, target, propertyKey?) -> var
.getOwnMetadata(metadataKey, target, propertyKey?) -> var
.hasMetadata(metadataKey, target, propertyKey?) -> bool
.hasOwnMetadata(metadataKey, target, propertyKey?) -> bool
.deleteMetadata(metadataKey, target, propertyKey?) -> bool
.getMetadataKeys(target, propertyKey?) -> array
.getOwnMetadataKeys(target, propertyKey?) -> array
.metadata(metadataKey, metadataValue) -> decorator(target, targetKey?) -> void
[1, 2, 3].includes(2); // => true
[1, 2, 3].includes(4); // => false
[1, 2, 3].includes(2, 2); // => false
[NaN].indexOf(NaN); // => -1
[NaN].includes(NaN); // => true
Array(1).indexOf(undefined); // => -1
Array(1).includes(undefined); // => true
'a๐ ฎทb'.at(1); // => '๐ ฎท'
'a๐ ฎทb'.at(1).length; // => 2
'hello'.padStart(10); // => ' hello'
'hello'.padStart(10, '1234'); // => '12341hello'
'hello'.padEnd(10); // => 'hello '
'hello'.padEnd(10, '1234'); // => 'hello12341'
' hello '.trimLeft(); // => 'hello '
' hello '.trimRight(); // => ' hello'
for(let [_, d, D] of '1111a2b3cccc'.matchAll(/(\d)(\D)/)){
console.log(d, D); // => 1 a, 2 b, 3 c
}
Object.values({a: 1, b: 2, c: 3}); // => [1, 2, 3]
Object.entries({a: 1, b: 2, c: 3}); // => [['a', 1], ['b', 2], ['c', 3]]
// Shallow object cloning with prototype and descriptors:
var copy = Object.create(Object.getPrototypeOf(O), Object.getOwnPropertyDescriptors(O));
// Mixin:
Object.defineProperties(target, Object.getOwnPropertyDescriptors(source));
JSON.stringify(new Map([['a', 'b'], ['c', 'd']])); // => '[["a","b"],["c","d"]]'
JSON.stringify(new Set([1, 2, 3, 2, 1])); // => '[1,2,3]'
System.global.Array === Array; // => true
Error.isError(new TypeError); // => true
var O = {};
Reflect.defineMetadata('foo', 'bar', O);
Reflect.ownKeys(O); // => []
Reflect.getOwnMetadataKeys(O); // => ['foo']
Reflect.getOwnMetadata('foo', O); // => 'bar'
core-js(/library)/web
Module web.timers
. Additional arguments fix for IE9-.
setTimeout(fn(...args), time, ...args) -> id
setInterval(fn(...args), time, ...args) -> id
core-js(/library)/web/timers
core-js(/library)/fn/set-timeout
core-js(/library)/fn/set-interval
// Before:
setTimeout(log.bind(null, 42), 1000);
// After:
setTimeout(log, 1000, 42);
Module web.immediate
. setImmediate
proposal polyfill.
setImmediate(fn(...args), ...args) -> id
clearImmediate(id) -> void
core-js(/library)/web/immediate
core-js(/library)/fn/set-immediate
core-js(/library)/fn/clear-immediate
setImmediate(function(arg1, arg2){
console.log(arg1, arg2); // => Message will be displayed with minimum delay
}, 'Message will be displayed', 'with minimum delay');
clearImmediate(setImmediate(function(){
console.log('Message will not be displayed');
}));
Some DOM collections should have iterable interface or should be inherited from Array
. That mean they should have keys
, values
, entries
and @@iterator
methods for iteration. So add them. Module web.dom.iterable
:
{
NodeList,
DOMTokenList,
MediaList,
StyleSheetList,
CSSRuleList
}
#values() -> iterator
#keys() -> iterator
#entries() -> iterator
#@@iterator() -> iterator (values)
core-js(/library)/web/dom-collections
core-js(/library)/fn/dom-collections/iterator
for(var {id} of document.querySelectorAll('*')){
if(id)console.log(id);
}
for(var [index, {id}] of document.querySelectorAll('*').entries()){
if(id)console.log(index, id);
}
core-js(/library)/core
Modules core.object.is-object
, core.object.classof
, core.object.define
, core.object.make
.
Object
.isObject(var) -> bool
.classof(var) -> string
.define(target, mixin) -> target
.make(proto | null, mixin?) -> object
core-js(/library)/core/object
core-js(/library)/fn/object/is-object
core-js(/library)/fn/object/define
core-js(/library)/fn/object/make
Object classify examples:
Object.isObject({}); // => true
Object.isObject(isNaN); // => true
Object.isObject(null); // => false
var classof = Object.classof;
classof(null); // => 'Null'
classof(undefined); // => 'Undefined'
classof(1); // => 'Number'
classof(true); // => 'Boolean'
classof('string'); // => 'String'
classof(Symbol()); // => 'Symbol'
classof(new Number(1)); // => 'Number'
classof(new Boolean(true)); // => 'Boolean'
classof(new String('string')); // => 'String'
var fn = function(){}
, list = (function(){return arguments})(1, 2, 3);
classof({}); // => 'Object'
classof(fn); // => 'Function'
classof([]); // => 'Array'
classof(list); // => 'Arguments'
classof(/./); // => 'RegExp'
classof(new TypeError); // => 'Error'
classof(new Set); // => 'Set'
classof(new Map); // => 'Map'
classof(new WeakSet); // => 'WeakSet'
classof(new WeakMap); // => 'WeakMap'
classof(new Promise(fn)); // => 'Promise'
classof([].values()); // => 'Array Iterator'
classof(new Set().values()); // => 'Set Iterator'
classof(new Map().values()); // => 'Map Iterator'
classof(Math); // => 'Math'
classof(JSON); // => 'JSON'
function Example(){}
Example.prototype[Symbol.toStringTag] = 'Example';
classof(new Example); // => 'Example'
Object.define
and Object.make
examples:
// Before:
Object.defineProperty(target, 'c', {
enumerable: true,
configurable: true,
get: function(){
return this.a + this.b;
}
});
// After:
Object.define(target, {
get c(){
return this.a + this.b;
}
});
// Shallow object cloning with prototype and descriptors:
var copy = Object.make(Object.getPrototypeOf(src), src);
// Simple inheritance:
function Vector2D(x, y){
this.x = x;
this.y = y;
}
Object.define(Vector2D.prototype, {
get xy(){
return Math.hypot(this.x, this.y);
}
});
function Vector3D(x, y, z){
Vector2D.apply(this, arguments);
this.z = z;
}
Vector3D.prototype = Object.make(Vector2D.prototype, {
constructor: Vector3D,
get xyz(){
return Math.hypot(this.x, this.y, this.z);
}
});
var vector = new Vector3D(9, 12, 20);
console.log(vector.xy); // => 15
console.log(vector.xyz); // => 25
vector.y++;
console.log(vector.xy); // => 15.811388300841896
console.log(vector.xyz); // => 25.495097567963924
Module core.dict
. Based on TC39 discuss / strawman.
[new] Dict(iterable (entries) | object ?) -> dict
.isDict(var) -> bool
.values(object) -> iterator
.keys(object) -> iterator
.entries(object) -> iterator (entries)
.has(object, key) -> bool
.get(object, key) -> val
.set(object, key, value) -> object
.forEach(object, fn(val, key, @), that) -> void
.map(object, fn(val, key, @), that) -> new @
.mapPairs(object, fn(val, key, @), that) -> new @
.filter(object, fn(val, key, @), that) -> new @
.some(object, fn(val, key, @), that) -> bool
.every(object, fn(val, key, @), that) -> bool
.find(object, fn(val, key, @), that) -> val
.findKey(object, fn(val, key, @), that) -> key
.keyOf(object, var) -> key
.includes(object, var) -> bool
.reduce(object, fn(memo, val, key, @), memo?) -> var
core-js(/library)/core/dict
core-js(/library)/fn/dict
Dict
create object without prototype from iterable or simple object.
var map = new Map([['a', 1], ['b', 2], ['c', 3]]);
Dict(); // => {__proto__: null}
Dict({a: 1, b: 2, c: 3}); // => {__proto__: null, a: 1, b: 2, c: 3}
Dict(map); // => {__proto__: null, a: 1, b: 2, c: 3}
Dict([1, 2, 3].entries()); // => {__proto__: null, 0: 1, 1: 2, 2: 3}
var dict = Dict({a: 42});
dict instanceof Object; // => false
dict.a; // => 42
dict.toString; // => undefined
'a' in dict; // => true
'hasOwnProperty' in dict; // => false
Dict.isDict({}); // => false
Dict.isDict(Dict()); // => true
Dict.keys
, Dict.values
and Dict.entries
returns iterators for objects.
var dict = {a: 1, b: 2, c: 3};
for(var key of Dict.keys(dict))console.log(key); // => 'a', 'b', 'c'
for(var val of Dict.values(dict))console.log(val); // => 1, 2, 3
for(var [key, val] of Dict.entries(dict)){
console.log(key); // => 'a', 'b', 'c'
console.log(val); // => 1, 2, 3
}
new Map(Dict.entries(dict)); // => Map {a: 1, b: 2, c: 3}
Basic dict operations for objects with prototype examples:
'q' in {q: 1}; // => true
'toString' in {}; // => true
Dict.has({q: 1}, 'q'); // => true
Dict.has({}, 'toString'); // => false
({q: 1})['q']; // => 1
({}).toString; // => function toString(){ [native code] }
Dict.get({q: 1}, 'q'); // => 1
Dict.get({}, 'toString'); // => undefined
var O = {};
O['q'] = 1;
O['q']; // => 1
O['__proto__'] = {w: 2};
O['__proto__']; // => {w: 2}
O['w']; // => 2
var O = {};
Dict.set(O, 'q', 1);
O['q']; // => 1
Dict.set(O, '__proto__', {w: 2});
O['__proto__']; // => {w: 2}
O['w']; // => undefined
Other methods of Dict
module are static equialents of Array.prototype
methods for dictionaries.
var dict = {a: 1, b: 2, c: 3};
Dict.forEach(dict, console.log, console);
// => 1, 'a', {a: 1, b: 2, c: 3}
// => 2, 'b', {a: 1, b: 2, c: 3}
// => 3, 'c', {a: 1, b: 2, c: 3}
Dict.map(dict, function(it){
return it * it;
}); // => {a: 1, b: 4, c: 9}
Dict.mapPairs(dict, function(val, key){
if(key != 'b')return [key + key, val * val];
}); // => {aa: 1, cc: 9}
Dict.filter(dict, function(it){
return it % 2;
}); // => {a: 1, c: 3}
Dict.some(dict, function(it){
return it === 2;
}); // => true
Dict.every(dict, function(it){
return it === 2;
}); // => false
Dict.find(dict, function(it){
return it > 2;
}); // => 3
Dict.find(dict, function(it){
return it > 4;
}); // => undefined
Dict.findKey(dict, function(it){
return it > 2;
}); // => 'c'
Dict.findKey(dict, function(it){
return it > 4;
}); // => undefined
Dict.keyOf(dict, 2); // => 'b'
Dict.keyOf(dict, 4); // => undefined
Dict.includes(dict, 2); // => true
Dict.includes(dict, 4); // => false
Dict.reduce(dict, function(memo, it){
return memo + it;
}); // => 6
Dict.reduce(dict, function(memo, it){
return memo + it;
}, ''); // => '123'
Module core.function.part
.
Function
#part(...args | _) -> fn(...args)
core-js/core/function
core-js(/library)/fn/function/part
core-js(/library)/fn/function/virtual/part
core-js(/library)/fn/_
Function#part
partial apply function without this
binding. Uses global variable _
(core._
for builds without global namespace pollution) as placeholder and not conflict with Underscore
/ LoDash
.
var fn1 = log.part(1, 2);
fn1(3, 4); // => 1, 2, 3, 4
var fn2 = log.part(_, 2, _, 4);
fn2(1, 3); // => 1, 2, 3, 4
var fn3 = log.part(1, _, _, 4);
fn3(2, 3); // => 1, 2, 3, 4
fn2(1, 3, 5); // => 1, 2, 3, 4, 5
fn2(1); // => 1, 2, undefined, 4
Module core.number.iterator
.
Number
#@@iterator() -> iterator
core-js(/library)/core/number
core-js(/library)/fn/number/iterator
core-js(/library)/fn/number/virtual/iterator
for(var i of 3)console.log(i); // => 0, 1, 2
[...10]; // => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Array.from(10, Math.random); // => [0.9817775336559862, 0.02720663254149258, ...]
Array.from(10, function(it){
return this + it * it;
}, .42); // => [0.42, 1.42, 4.42, 9.42, 16.42, 25.42, 36.42, 49.42, 64.42, 81.42]
Modules core.regexp.escape
, core.string.escape-html
and core.string.unescape-html
.
RegExp
.escape(str) -> str
String
#escapeHTML() -> str
#unescapeHTML() -> str
core-js(/library)/core/regexp
core-js(/library)/core/string
core-js(/library)/fn/regexp/escape
core-js(/library)/fn/string/escape-html
core-js(/library)/fn/string/unescape-html
core-js(/library)/fn/string/virtual/escape-html
core-js(/library)/fn/string/virtual/unescape-html
RegExp.escape('Hello, []{}()*+?.\\^$|!'); // => 'Hello, \[\]\{\}\(\)\*\+\?\.\\\^\$\|!'
'<script>doSomething();</script>'.escapeHTML(); // => '<script>doSomething();</script>'
'<script>doSomething();</script>'.unescapeHTML(); // => '<script>doSomething();</script>'
Module core.delay
. Promise-returning delay function, esdiscuss.
delay(ms) -> promise
core-js(/library)/core/delay
core-js(/library)/fn/delay
delay(1e3).then(() => console.log('after 1 sec'));
(async () => {
await delay(3e3);
console.log('after 3 sec');
while(await delay(3e3))console.log('each 3 sec');
})();
Modules core.is-iterable
, core.get-iterator
, core.get-iterator-method
- helpers for check iterability / get iterator in the library
version or, for example, for arguments
object:
core
.isIterable(var) -> bool
.getIterator(iterable) -> iterator
.getIteratorMethod(var) -> function | undefined
core-js(/library)/fn/is-iterable
core-js(/library)/fn/get-iterator
core-js(/library)/fn/get-iterator-method
var list = (function(){
return arguments;
})(1, 2, 3);
console.log(core.isIterable(list)); // true;
var iter = core.getIterator(list);
console.log(iter.next().value); // 1
console.log(iter.next().value); // 2
console.log(iter.next().value); // 3
console.log(iter.next().value); // undefined
core.getIterator({}); // TypeError: [object Object] is not iterable!
var iterFn = core.getIteratorMethod(list);
console.log(typeof iterFn); // 'function'
var iter = iterFn.call(list);
console.log(iter.next().value); // 1
console.log(iter.next().value); // 2
console.log(iter.next().value); // 3
console.log(iter.next().value); // undefined
console.log(core.getIteratorMethod({})); // undefined
- ES5
JSON
is missing now only in IE7- and never will it be added tocore-js
, if you need it in these old browsers, many implementations are available, for example, json3. - ES6
String#normalize
is not a very useful feature, but this polyfill will be very large. If you need it, you can use unorm. - ES6
Proxy
can't be polyfilled, but for Node.js / Chromium with additional flags you can try harmony-reflect for adapt old styleProxy
API to final ES6 version. - ES6 logic for
@@isConcatSpreadable
and@@species
(in most places) can be polyfilled without problems, but it will cause a serious slowdown in popular cases in some engines. It will be polyfilled when it will be implemented in modern engines. - ES7
SIMD
.core-js
doesn't add polyfill of this feature because of large size and some other reasons. You can use this polyfill. window.fetch
is not a cross-platform feature, in some environments it makes no sense. For this reason, I don't think it should be incore-js
. Looking at a large number of requests it may be added in the future. Now you can use, for example, this polyfill.- ECMA-402
Intl
is missed because of size. You can use this polyfill.