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It's documentation for obsolete core-js@2. If you looking documentation for actual core-js version, please, check this branch.
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.
Example:
js
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:
js
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
npm i core-js
bower install core.js
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:
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.
```js 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 [ES6Arrayfeatures](#ecmascript-6-array),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 up core-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:
```js
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:
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.
CommonJS entry points:
core-js(/library) <- all features
core-js(/library)/shim <- only polyfills
All features moved to the es6 namespace, here just a list of features:
js
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
CommonJS entry points:
core-js(/library)/es5
CommonJS entry points:
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.
js
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
CommonJS entry points:
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
Examples:
```js
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.
js
Function
#bind(object, ...args) -> boundFn(...args)
#name -> string (IE9+)
#@@hasInstance(var) -> bool
CommonJS entry points:
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
Example:
```js
(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.
js
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)
CommonJS entry points:
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
Examples:
```js
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.
js
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)
CommonJS entry 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
Examples:
```js
for(var val of 'a𠮷b'){
console.log(val); // => 'a', '𠮷', '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'
'𠮷'.codePointAt(0); // => 134071 String.fromCodePoint(97, 134071, 98); // => 'a𠮷b'
var name = 'Bob';
String.rawHi\n${name}!; // => 'Hi\nBob!' (ES6 template string syntax)
String.raw({raw: 'test'}, 0, 1, 2); // => 't0e1s2t'
'foo'.bold(); // => 'foo' 'bar'.anchor('a"b'); // => 'bar' 'baz'.link('http://example.com'); // => 'baz' ```
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
CommonJS entry points:
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
Examples:
```js
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:
js
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.
js
[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
CommonJS entry points:
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.
js
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
CommonJS entry points:
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.
js
Date
.now() -> int
#toISOString() -> string
#toJSON() -> string
#toString() -> string
#@@toPrimitive(hint) -> primitive
CommonJS entry points:
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
Example:
js
new Date(NaN).toString(); // => 'Invalid Date'
Module es6.promise.
js
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
CommonJS entry points:
core-js(/library)/es6/promise
core-js(/library)/fn/promise
Basic example:
```js
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*](http://goo.gl/vr8TN3):js
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*](http://goo.gl/RdoDBZ):js
Promise.all([
'foo',
sleepRandom(5),
sleepRandom(15),
sleepRandom(10) // after 15 sec:
]).then(x => console.log(x)); // => ['foo', 956, 85, 382]
`Promise.race` [*example*](http://goo.gl/L8ovkJ):js
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](https://tc39.github.io/ecmascript-asyncawait) [example](http://goo.gl/wnQS4j):js
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:
```js
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*](http://goo.gl/Wozskl):js
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.
js
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.
js
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
CommonJS entry points:
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
Basic example:
```js
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*](http://goo.gl/0pdJjX):js
var symbol = Symbol.for('key');
symbol === Symbol.for('key'); // true
Symbol.keyFor(symbol); // 'key'
[*Example*](http://goo.gl/mKVOQJ) with methods for getting own object keys:js
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)]
```
Symbol polyfill:Symbol returns object.Symbol.for and Symbol.keyFor can't be shimmed cross-realm.Symbol polyfill defines setter in Object.prototype. For this reason, uncontrolled creation of symbols can cause memory leak and the in operator is not working correctly with Symbol polyfill: Symbol() in {} // => true.You can disable defining setters in Object.prototype. Example:
```js
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-jsnot adds setters toObject.prototypefor 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, IElocalStorage`).
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.
js
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)
CommonJS entry points:
core-js(/library)/es6/map
core-js(/library)/fn/map
Examples:
```js
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.
js
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)
CommonJS entry points:
core-js(/library)/es6/set
core-js(/library)/fn/set
Examples:
```js
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.
js
new WeakMap(iterable (entries) ?) -> weakmap
#delete(key) -> bool
#get(key) -> val
#has(key) -> bool
#set(key, val) -> @
CommonJS entry points:
core-js(/library)/es6/weak-map
core-js(/library)/fn/weak-map
Examples:
```js
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.
js
new WeakSet(iterable?) -> weakset
#add(key) -> @
#delete(key) -> bool
#has(key) -> bool
CommonJS entry points:
core-js(/library)/es6/weak-set
core-js(/library)/fn/weak-set
Examples:
```js
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 ```
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.
```js
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
#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
[*CommonJS entry points:*](#commonjs)
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
[*Examples*](http://goo.gl/yla75z):js
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 } ```
Uint8ClampedArray in IE10 and early IE11), all modern engines have native typed arrays and requires only constructors fixes and methods.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.
js
Reflect
.apply(target, thisArgument, argumentsList) -> var
.construct(target, argumentsList, newTarget?) -> object
.defineProperty(target, propertyKey, attributes) -> bool
.deleteProperty(target, propertyKey) -> bool
.enumerate(target) -> iterator (removed from the spec and will be removed from core-js@3)
.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+)
CommonJS entry points:
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
Examples:
```js
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 ```
CommonJS entry points:
core-js(/library)/es7
core-js(/library)/es7/array
core-js(/library)/es7/global
core-js(/library)/es7/string
core-js(/library)/es7/map
core-js(/library)/es7/set
core-js(/library)/es7/error
core-js(/library)/es7/math
core-js(/library)/es7/system
core-js(/library)/es7/symbol
core-js(/library)/es7/reflect
core-js(/library)/es7/observable
core-js/stage/4 entry point contains only stage 4 proposals, core-js/stage/3 - stage 3 and stage 4, etc.
CommonJS entry points:
js
core-js(/library)/stage/4
* {Array, %TypedArray%}#includes proposal - module es7.array.includes, %TypedArray% version in modules from this section.
js
Array
#includes(var, from?) -> bool
{
Int8Array,
Uint8Array,
Uint8ClampedArray,
Int16Array,
Uint16Array,
Int32Array,
Uint32Array,
Float32Array,
Float64Array
}
#includes(var, from?) -> bool
CommonJS entry points:
js
core-js(/library)/fn/array/includes
Examples:
```js
[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
* `Object.values`, `Object.entries` [proposal](https://github.com/tc39/proposal-object-values-entries) - modules [`es7.object.values`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.object.values.js), [`es7.object.entries`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.object.entries.js)js
Object
.values(object) -> array
.entries(object) -> array
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/object/values
core-js(/library)/fn/object/entries
[*Examples*](http://goo.gl/6kuGOn):js
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]]
for(let [key, value] of Object.entries({a: 1, b: 2, c: 3})){
console.log(key); // => 'a', 'b', 'c'
console.log(value); // => 1, 2, 3
}
* `Object.getOwnPropertyDescriptors` [proposal](https://github.com/tc39/proposal-object-getownpropertydescriptors) - module [`es7.object.get-own-property-descriptors`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.object.get-own-property-descriptors.js)js
Object
.getOwnPropertyDescriptors(object) -> object
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/object/get-own-property-descriptors
*Examples*:js
// Shallow object cloning with prototype and descriptors:
var copy = Object.create(Object.getPrototypeOf(O), Object.getOwnPropertyDescriptors(O));
// Mixin:
Object.defineProperties(target, Object.getOwnPropertyDescriptors(source));
* `String#padStart`, `String#padEnd` [proposal](https://github.com/tc39/proposal-string-pad-start-end) - modules [`es7.string.pad-start`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.string.pad-start.js), [`es7.string.pad-end`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.string.pad-end.js)js
String
#padStart(length, fillStr = ' ') -> string
#padEnd(length, fillStr = ' ') -> string
[*CommonJS entry points:*](#commonjs)js
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
[*Examples*](http://goo.gl/hK5ccv):js
'hello'.padStart(10); // => ' hello'
'hello'.padStart(10, '1234'); // => '12341hello'
'hello'.padEnd(10); // => 'hello '
'hello'.padEnd(10, '1234'); // => 'hello12341'
* `Object#__(define|lookup)[GS]etter__`, [annex B ES2017](https://github.com/tc39/ecma262/pull/381), but we haven't special namespace for that - modules [`es7.object.define-setter`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.object.define-setter.js), [`es7.object.define-getter`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.object.define-getter.js), [`es7.object.lookup-setter`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.object.lookup-setter.js) and [`es7.object.lookup-getter`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.object.lookup-getter.js).js
Object
#defineSetter(key, fn) -> void
#defineGetter(key, fn) -> void
#lookupSetter(key) -> fn | void
#lookupGetter(key) -> fn | void
[*CommonJS entry points:*](#commonjs)js
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
```
CommonJS entry points:
js
core-js(/library)/stage/3
* global proposal - modules es7.global and es7.system.global (obsolete)
js
global -> object
System
.global -> object (obsolete)
CommonJS entry points:
js
core-js(/library)/fn/global
core-js(/library)/fn/system/global (obsolete)
Examples:
js
global.Array === Array; // => true
* Promise#finally proposal - module es7.promise.finally
js
Promise
#finally(onFinally()) -> promise
CommonJS entry points:
js
core-js(/library)/fn/promise/finally
Examples:
```js
Promise.resolve(42).finally(() => console.log('You will see it anyway'));
Promise.reject(42).finally(() => console.log('You will see it anyway'));
CommonJS entry points:
js
core-js(/library)/stage/2
* String#trimLeft, String#trimRight / String#trimStart, String#trimEnd proposal - modules es7.string.trim-left, es7.string.trim-right
js
String
#trimLeft() -> string
#trimRight() -> string
#trimStart() -> string
#trimEnd() -> string
CommonJS entry points:
js
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/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
Examples:
js
' hello '.trimLeft(); // => 'hello '
' hello '.trimRight(); // => ' hello'
* `Symbol.asyncIterator` for [async iteration proposal](https://github.com/tc39/proposal-async-iteration) - module [`es7.symbol.async-iterator`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.symbol.async-iterator.js)js
Symbol
.asyncIterator -> @@asyncIterator
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/symbol/async-iterator
```
CommonJS entry points:
js
core-js(/library)/stage/1
* Promise.try proposal - module es7.promise.try
js
Promise
.try(function()) -> promise
CommonJS entry points:
js
core-js(/library)/fn/promise/try
Examples:
``js
Promise.try(() => 42).then(it => console.log(Promise, resolved as ${it}`));
Promise.try(() => { throw 42; }).catch(it => console.log(Promise, rejected as ${it}));
* `Array#flatten` and `Array#flatMap` [proposal](https://tc39.github.io/proposal-flatMap) - modules [`es7.array.flatten`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.array.flatten.js) and [`es7.array.flat-map`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.array.flat-map.js)js
Array
#flatten(depthArg = 1) -> array
#flatMap(fn(val, key, @), that) -> array
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/array/flatten
core-js(/library)/fn/array/flat-map
core-js(/library)/fn/array/virtual/flatten
core-js(/library)/fn/array/virtual/flat-map
[*Examples*](https://goo.gl/jTXsZi):js
[1, [2, 3], [4, 5]].flatten(); // => [1, 2, 3, 4, 5]
[1, [2, [3, [4]]], 5].flatten(); // => [1, 2, [3, [4]], 5]
[1, [2, [3, [4]]], 5].flatten(3); // => [1, 2, 3, 4, 5]
[{a: 1, b: 2}, {a: 3, b: 4}, {a: 5, b: 6}].flatMap(it => [it.a, it.b]); // => [1, 2, 3, 4, 5, 6]
* `.of` and `.from` methods on collection constructors [proposal](https://github.com/tc39/proposal-setmap-offrom) - modules [`es7.set.of`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.set.of.js), [`es7.set.from`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.set.from.js), [`es7.map.of`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.map.of.js), [`es7.map.from`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.map.from.js), [`es7.weak-set.of`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.weak-set.of.js), [`es7.weak-set.from`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.weak-set.from.js), [`es7.weak-map.of`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.weak-map.of.js), [`es7.weak-map.from`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.weak-map.from.js)js
Set
.of(...args) -> set
.from(iterable, mapFn(val, index)?, that?) -> set
Map
.of(...args) -> map
.from(iterable, mapFn(val, index)?, that?) -> map
WeakSet
.of(...args) -> weakset
.from(iterable, mapFn(val, index)?, that?) -> weakset
WeakMap
.of(...args) -> weakmap
.from(iterable, mapFn(val, index)?, that?) -> weakmap
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/set/of
core-js(/library)/fn/set/from
core-js(/library)/fn/map/of
core-js(/library)/fn/map/from
core-js(/library)/fn/weak-set/of
core-js(/library)/fn/weak-set/from
core-js(/library)/fn/weak-map/of
core-js(/library)/fn/weak-map/from
[*Examples*](https://goo.gl/mSC7eU):js
Set.of(1, 2, 3, 2, 1); // => Set {1, 2, 3}
Map.from([[1, 2], [3, 4]], ([key, val]) => [key ** 2, val ** 2]); // => Map {1: 4, 9: 16}
* `String#matchAll` [proposal](https://github.com/tc39/String.prototype.matchAll) - module [`es7.string.match-all`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.string.match-all.js)js
String
#matchAll(regexp) -> iterator
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/string/match-all
core-js(/library)/fn/string/virtual/match-all
[*Examples*](http://goo.gl/6kp9EB):js
for(let [, d, D] of '1111a2b3cccc'.matchAll(/(\d)(\D)/)){
console.log(d, D); // => 1 a, 2 b, 3 c
}
* `Observable` [proposal](https://github.com/zenparsing/es-observable) - modules [`es7.observable`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.observable.js) and [`es7.symbol.observable`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.symbol.observable.js)js
new Observable(fn) -> observable
#subscribe(observer) -> subscription
#forEach(fn) -> promise
#@@observable() -> @
.of(...items) -> observable
.from(observable | iterable) -> observable
.@@species -> @
Symbol
.observable -> @@observable
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/observable
core-js(/library)/fn/symbol/observable
[*Examples*](http://goo.gl/1LDywi):js
new Observable(observer => {
observer.next('hello');
observer.next('world');
observer.complete();
}).forEach(it => console.log(it))
.then( => console.log('!'));
* `Math.{clamp, DEG_PER_RAD, degrees, fscale, rad-per-deg, radians, scale}`
[proposal](https://github.com/rwaldron/proposal-math-extensions) - modules
[`es7.math.clamp`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.clamp.js),
[`es7.math.DEG_PER_RAD`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.DEG_PER_RAD.js),
[`es7.math.degrees`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.degrees.js),
[`es7.math.fscale`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.fscale.js),
[`es7.math.RAD_PER_DEG`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.RAD_PER_DEG.js),
[`es7.math.radians`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.radians.js) and
[`es7.math.scale`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.scale.js)js
Math
.DEG_PER_RAD -> number
.RAD_PER_DEG -> number
.clamp(x, lower, upper) -> number
.degrees(radians) -> number
.fscale(x, inLow, inHigh, outLow, outHigh) -> number
.radians(degrees) -> number
.scale(x, inLow, inHigh, outLow, outHigh) -> number
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/math/clamp
core-js(/library)/fn/math/deg-per-rad
core-js(/library)/fn/math/degrees
core-js(/library)/fn/math/fscale
core-js(/library)/fn/math/rad-per-deg
core-js(/library)/fn/math/radians
core-js(/library)/fn/math/scale
* `Math.signbit` [proposal](http://jfbastien.github.io/papers/Math.signbit.html) - module [`es7.math.signbit`](https://github.com/zloirock/core-js/blob/v2.6.12/modules/es7.math.signbit.js)js
Math
.signbit(x) -> bool
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/fn/math/signbit
[*Examples*](http://es6.zloirock.ru/):js
Math.signbit(NaN); // => NaN
Math.signbit(1); // => true
Math.signbit(-1); // => false
Math.signbit(0); // => true
Math.signbit(-0); // => false
```
CommonJS entry points:
js
core-js(/library)/stage/0
* String#at proposal - module es7.string.at
js
String
#at(index) -> string
CommonJS entry points:
js
core-js(/library)/fn/string/at
core-js(/library)/fn/string/virtual/at
Examples:
js
'a𠮷b'.at(1); // => '𠮷'
'a𠮷b'.at(1).length; // => 2
* Map#toJSON, Set#toJSON proposal - modules es7.map.to-json, es7.set.to-json (rejected and will be removed from core-js@3)
js
Map
#toJSON() -> array (rejected and will be removed from core-js@3)
Set
#toJSON() -> array (rejected and will be removed from core-js@3)
CommonJS entry points:
js
core-js(/library)/fn/map
core-js(/library)/fn/set
* Error.isError proposal - module es7.error.is-error (withdrawn and will be removed from core-js@3)
js
Error
.isError(it) -> bool (withdrawn and will be removed from core-js@3)
CommonJS entry points:
js
core-js(/library)/fn/error/is-error
* Math.{iaddh, isubh, imulh, umulh} proposal - modules es7.math.iaddh, es7.math.isubh, es7.math.imulh and es7.math.umulh
js
Math
.iaddh(lo0, hi0, lo1, hi1) -> int32
.isubh(lo0, hi0, lo1, hi1) -> int32
.imulh(a, b) -> int32
.umulh(a, b) -> uint32
CommonJS entry points:
js
core-js(/library)/fn/math/iaddh
core-js(/library)/fn/math/isubh
core-js(/library)/fn/math/imulh
core-js(/library)/fn/math/umulh
* global.asap, TC39 discussion, module es7.asap
js
asap(fn) -> void
CommonJS entry points:
js
core-js(/library)/fn/asap
Examples:
js
asap(() => console.log('called as microtask'));
CommonJS entry points:
js
core-js(/library)/stage/pre
* Reflect metadata proposal - modules es7.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 and es7.reflect.metadata.
js
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
CommonJS entry points:
js
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
Examples:
js
var O = {};
Reflect.defineMetadata('foo', 'bar', O);
Reflect.ownKeys(O); // => []
Reflect.getOwnMetadataKeys(O); // => ['foo']
Reflect.getOwnMetadata('foo', O); // => 'bar'
CommonJS entry points:
js
core-js(/library)/web
Module web.timers. Additional arguments fix for IE9-.
js
setTimeout(fn(...args), time, ...args) -> id
setInterval(fn(...args), time, ...args) -> id
CommonJS entry points:
js
core-js(/library)/web/timers
core-js(/library)/fn/set-timeout
core-js(/library)/fn/set-interval
js
// Before:
setTimeout(log.bind(null, 42), 1000);
// After:
setTimeout(log, 1000, 42);
Module web.immediate. setImmediate proposal polyfill.
js
setImmediate(fn(...args), ...args) -> id
clearImmediate(id) -> void
CommonJS entry points:
js
core-js(/library)/web/immediate
core-js(/library)/fn/set-immediate
core-js(/library)/fn/clear-immediate
Examples:
```js
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:
```js
{
CSSRuleList,
CSSStyleDeclaration,
CSSValueList,
ClientRectList,
DOMRectList,
DOMStringList,
DOMTokenList,
DataTransferItemList,
FileList,
HTMLAllCollection,
HTMLCollection,
HTMLFormElement,
HTMLSelectElement,
MediaList,
MimeTypeArray,
NamedNodeMap,
NodeList,
PaintRequestList,
Plugin,
PluginArray,
SVGLengthList,
SVGNumberList,
SVGPathSegList,
SVGPointList,
SVGStringList,
SVGTransformList,
SourceBufferList,
StyleSheetList,
TextTrackCueList,
TextTrackList,
TouchList
}
#@@iterator() -> iterator (values)
{
DOMTokenList,
NodeList
}
#values() -> iterator
#keys() -> iterator
#entries() -> iterator
[*CommonJS entry points:*](#commonjs)js
core-js(/library)/web/dom-collections
core-js(/library)/fn/dom-collections/iterator
[*Examples*](http://goo.gl/lfXVFl):js
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); } ```
CommonJS entry points:
js
core-js(/library)/core
Modules core.object.is-object, core.object.classof, core.object.define, core.object.make.
js
Object
.isObject(var) -> bool
.classof(var) -> string
.define(target, mixin) -> target
.make(proto | null, mixin?) -> object
CommonJS entry points:
js
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:
```js
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*](http://goo.gl/rtpD5Z):js
// 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.
js
[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
CommonJS entry points:
js
core-js(/library)/core/dict
core-js(/library)/fn/dict
Dict create object without prototype from iterable or simple object.
Examples: ```js 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.valuesandDict.entries` returns iterators for objects.
Examples: ```js 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*](http://goo.gl/B28UnG):js
'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 ofDictmodule are static equivalents ofArray.prototype` methods for dictionaries.
Examples: ```js 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.
js
Function
#part(...args | _) -> fn(...args)
CommonJS entry points:
js
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.
Examples: ```js 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.
js
Number
#@@iterator() -> iterator
CommonJS entry points:
js
core-js(/library)/core/number
core-js(/library)/fn/number/iterator
core-js(/library)/fn/number/virtual/iterator
Examples:
```js
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.
js
RegExp
.escape(str) -> str
String
#escapeHTML() -> str
#unescapeHTML() -> str
CommonJS entry points:
js
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
Examples:
```js
RegExp.escape('Hello, []{}()*+?.\^$|!'); // => 'Hello, []{}()*+\?.\\^\$\|!'
''.escapeHTML(); // => '<script>doSomething();</script>' '<script>doSomething();</script>'.unescapeHTML(); // => '' ```
Module core.delay. Promise-returning delay function, esdiscuss.
js
delay(ms) -> promise
CommonJS entry points:
js
core-js(/library)/core/delay
core-js(/library)/fn/delay
Examples:
```js
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:
js
core
.isIterable(var) -> bool
.getIterator(iterable) -> iterator
.getIteratorMethod(var) -> function | undefined
CommonJS entry points:
js
core-js(/library)/fn/is-iterable
core-js(/library)/fn/get-iterator
core-js(/library)/fn/get-iterator-method
Examples:
```js
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 ```
JSON is missing now only in IE7- and never will it be added to core-js, if you need it in these old browsers, many implementations are available, for example, json3.String#normalize is not a very useful feature, but this polyfill will be very large. If you need it, you can use unorm.Proxy can't be polyfilled, but for Node.js / Chromium with additional flags you can try harmony-reflect for adapt old style Proxy API to final ES6 version.@@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.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 in core-js. Looking at a large number of requests it may be added in the future. Now you can use, for example, this polyfill.Intl is missed because of size. You can use this polyfill.