I highly recommend reading this: So, what's next?
Modular standard library for JavaScript. Includes polyfills for ECMAScript up to 2024: promises, symbols, collections, iterators, typed arrays, many other features, ECMAScript proposals, some cross-platform WHATWG / W3C features and proposals like
URL. You can load only required features or use it without global namespace pollution.
If you are looking for documentation for obsolete core-js@2, please, check this branch.
Raising funds
core-js isn't backed by a company, so the future of this project depends on you. Become a sponsor or a backer if you are interested in core-js: Open Collective, Patreon, Boosty, Bitcoin ( bc1qlea7544qtsmj2rayg0lthvza9fau63ux0fstcz ), Alipay.
import 'core-js/actual';
Promise.resolve(42).then(it => console.log(it)); // => 42
Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]
[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]
(function * (i) { while (true) yield i++; })(1)
.drop(1).take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])You can load only required features:
import 'core-js/actual/promise';
import 'core-js/actual/set';
import 'core-js/actual/iterator';
import 'core-js/actual/array/from';
import 'core-js/actual/array/flat-map';
import 'core-js/actual/structured-clone';
Promise.resolve(42).then(it => console.log(it)); // => 42
Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]
[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]
(function * (i) { while (true) yield i++; })(1)
.drop(1).take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])Or use it without global namespace pollution:
import Promise from 'core-js-pure/actual/promise';
import Set from 'core-js-pure/actual/set';
import Iterator from 'core-js-pure/actual/iterator';
import from from 'core-js-pure/actual/array/from';
import flatMap from 'core-js-pure/actual/array/flat-map';
import structuredClone from 'core-js-pure/actual/structured-clone';
Promise.resolve(42).then(it => console.log(it)); // => 42
from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]
flatMap([1, 2], it => [it, it]); // => [1, 1, 2, 2]
Iterator.from(function * (i) { while (true) yield i++; }(1))
.drop(1).take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])Index
- Usage
- Supported engines and compatibility data
- Features
- ECMAScript
- ECMAScript: Object
- ECMAScript: Function
- ECMAScript: Error
- ECMAScript: Array
- ECMAScript: String and RegExp
- ECMAScript: Number
- ECMAScript: Math
- ECMAScript: Date
- ECMAScript: Promise
- ECMAScript: Symbol
- ECMAScript: Collections
- ECMAScript: Typed Arrays
- ECMAScript: Reflect
- ECMAScript: JSON
- ECMAScript: globalThis
- ECMAScript proposals
- Finished proposals
globalThis- Relative indexing method
Array.prototype.includesArray.prototype.flat/Array.prototype.flatMapArrayfind from last- Change
Arrayby copy ArraygroupingArrayBuffer.prototype.transferand friendsObject.values/Object.entriesObject.fromEntriesObject.getOwnPropertyDescriptors- Accessible
Object.prototype.hasOwnProperty StringpaddingString.prototype.matchAllString.prototype.replaceAllString.prototype.trimStart/String.prototype.trimEndRegExps(dotAll) flagRegExpnamed capture groupsPromise.allSettledPromise.anyPromise.prototype.finallyPromise.withResolversSymbol.asyncIteratorfor asynchronous iterationSymbol.prototype.description- Well-formed
JSON.stringify - Well-formed unicode strings
- New
Setmethods
- Stage 3 proposals
- Stage 2.7 proposals
- Stage 2 proposals
- Stage 1 proposals
Observable- New collections methods
.ofand.frommethods on collection constructorscompositeKeyandcompositeSymbolArrayfilteringArraydeduplicationDataViewget / setUint8ClampedmethodsNumber.fromStringString.cookedString.prototype.codePointsSymbol.customMatcherfor pattern matchingSymbol.customMatcherfor extractors
- Stage 0 proposals
- Pre-stage 0 proposals
- Finished proposals
- Web standards
- Iteration helpers
- ECMAScript
- Missing polyfills
- Contributing
- Security policy
- Changelog
Usage⬆
Installation:⬆
// global version
npm install --save core-js@3.37.0
// version without global namespace pollution
npm install --save core-js-pure@3.37.0
// bundled global version
npm install --save core-js-bundle@3.37.0Or you can use core-js from CDN.
postinstall message⬆
The core-js project needs your help, so the package shows a message about it after installation. If it causes problems for you, you can disable it:
ADBLOCK=true npm install
// or
DISABLE_OPENCOLLECTIVE=true npm install
// or
npm install --loglevel silentCommonJS API⬆
You can import only-required-for-you polyfills, like in examples at the top of README.md. Available CommonJS entry points for all polyfilled methods / constructors and namespaces. Just some examples:
// polyfill all `core-js` features, including early-stage proposals:
import "core-js";
// or:
import "core-js/full";
// polyfill all actual features - stable ES, web standards and stage 3 ES proposals:
import "core-js/actual";
// polyfill only stable features - ES and web standards:
import "core-js/stable";
// polyfill only stable ES features:
import "core-js/es";
// if you want to polyfill `Set`:
// all `Set`-related features, with early-stage ES proposals:
import "core-js/full/set";
// stable required for `Set` ES features, features from web standards and stage 3 ES proposals:
import "core-js/actual/set";
// stable required for `Set` ES features and features from web standards
// (DOM collections iterator in this case):
import "core-js/stable/set";
// only stable ES features required for `Set`:
import "core-js/es/set";
// the same without global namespace pollution:
import Set from "core-js-pure/full/set";
import Set from "core-js-pure/actual/set";
import Set from "core-js-pure/stable/set";
import Set from "core-js-pure/es/set";
// if you want to polyfill just required methods:
import "core-js/full/set/intersection";
import "core-js/actual/array/find-last";
import "core-js/stable/queue-microtask";
import "core-js/es/array/from";
// polyfill iterator helpers proposal:
import "core-js/proposals/iterator-helpers";
// polyfill all stage 2+ proposals:
import "core-js/stage/2";Note: The usage of the /actual/ namespace is recommended since it includes all actual JavaScript features and does not include unstable early-stage proposals that are available mainly for experiments.
Caveats when using CommonJS API:⬆
modulespath is an 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.- If you use
core-jswith the extension of native objects, recommended load allcore-jsmodules at the top of the entry point of your application, otherwise, you can have conflicts.- For example, Google Maps use their own
Symbol.iterator, conflicting withArray.from,URLSearchParamsand/or something else fromcore-js, see related issues. - Such conflicts also resolvable by discovering and manual adding each conflicting entry from
core-js.
- For example, Google Maps use their own
core-jsis extremely modular and uses a lot of very tiny modules, because of that for usage in browsers bundle upcore-jsinstead of usage loader for each file, otherwise, you will have hundreds of requests.
CommonJS and prototype methods without global namespace pollution⬆
In the pure version, we can't pollute prototypes of native constructors. Because of that, prototype methods transformed into static methods like in examples above. 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-pure/actual/array/virtual/fill';
import findIndex from 'core-js-pure/actual/array/virtual/find-index';
Array(10)::fill(0).map((a, b) => b * b)::findIndex(it => it && !(it % 8)); // => 4Warning! The bind operator is an early-stage ECMAScript proposal and usage of this syntax can be dangerous.
Babel⬆
core-js is integrated with babel and is the base for polyfilling-related babel features:
@babel/polyfill⬆
@babel/polyfill IS just the import of stable core-js features and regenerator-runtime for generators and async functions, so if you load @babel/polyfill - you load the global version of core-js without ES proposals.
Now it's deprecated in favour of separate inclusion of required parts of core-js and regenerator-runtime and, for preventing breaking changes, left on core-js@2.
As a full equal of @babel/polyfill, you can use this:
import 'core-js/stable';
import 'regenerator-runtime/runtime';@babel/preset-env⬆
@babel/preset-env has useBuiltIns option, which optimizes working with global version of core-js. With useBuiltIns option, you should also set corejs option to used version of core-js, like corejs: '3.37'.
Warning! Recommended to specify used minor
core-jsversion, likecorejs: '3.37', instead ofcorejs: 3, since withcorejs: 3will not be injected modules which were added in minorcore-jsreleases.
useBuiltIns: 'entry'replaces imports ofcore-jsto import only required for a target environment modules. So, for example,
import 'core-js/stable';with chrome 71 target will be replaced just to:
import "core-js/modules/es.array.unscopables.flat";
import "core-js/modules/es.array.unscopables.flat-map";
import "core-js/modules/es.object.from-entries";
import "core-js/modules/web.immediate";It works for all entry points of global version of core-js and their combinations, for example for
import 'core-js/es';
import 'core-js/proposals/set-methods';
import 'core-js/full/set/map';with chrome 71 target you will have as a result:
import "core-js/modules/es.array.unscopables.flat";
import "core-js/modules/es.array.unscopables.flat-map";
import "core-js/modules/es.object.from-entries";
import "core-js/modules/esnext.set.difference";
import "core-js/modules/esnext.set.intersection";
import "core-js/modules/esnext.set.is-disjoint-from";
import "core-js/modules/esnext.set.is-subset-of";
import "core-js/modules/esnext.set.is-superset-of";
import "core-js/modules/esnext.set.map";
import "core-js/modules/esnext.set.symmetric-difference";
import "core-js/modules/esnext.set.union";useBuiltIns: 'usage'adds to the top of each file import of polyfills for features used in this file and not supported by target environments, so for:
// first file:
var set = new Set([1, 2, 3]);
// second file:
var array = Array.of(1, 2, 3);if target contains an old environment like IE 11 we will have something like:
// first file:
import 'core-js/modules/es.array.iterator';
import 'core-js/modules/es.object.to-string';
import 'core-js/modules/es.set';
var set = new Set([1, 2, 3]);
// second file:
import 'core-js/modules/es.array.of';
var array = Array.of(1, 2, 3);By default, @babel/preset-env with useBuiltIns: 'usage' option only polyfills stable features, but you can enable polyfilling of proposals by proposals option, as corejs: { version: '3.37', proposals: true }.
Warning! In the case of
useBuiltIns: 'usage', you should not addcore-jsimports by yourself, they will be added automatically.
@babel/runtime⬆
@babel/runtime with corejs: 3 option simplifies work with core-js-pure. It automatically replaces usage of modern features from JS standard library to imports from the version of core-js without global namespace pollution, so instead of:
import from from 'core-js-pure/stable/array/from';
import flat from 'core-js-pure/stable/array/flat';
import Set from 'core-js-pure/stable/set';
import Promise from 'core-js-pure/stable/promise';
from(new Set([1, 2, 3, 2, 1]));
flat([1, [2, 3], [4, [5]]], 2);
Promise.resolve(32).then(x => console.log(x));you can write just:
Array.from(new Set([1, 2, 3, 2, 1]));
[1, [2, 3], [4, [5]]].flat(2);
Promise.resolve(32).then(x => console.log(x));By default, @babel/runtime only polyfills stable features, but like in @babel/preset-env, you can enable polyfilling of proposals by proposals option, as corejs: { version: 3, proposals: true }.
Warning! If you use
@babel/preset-envand@babel/runtimetogether, usecorejsoption only in one place since it's duplicate functionality and will cause conflicts.
swc⬆
Fast JavaScript transpiler swc contains integration with core-js, that optimizes work with the global version of core-js. Like @babel/preset-env, it has 2 modes: usage and entry, but usage mode still works not so good like in babel. Example of configuration in .swcrc:
{
"env": {
"targets": "> 0.25%, not dead",
"mode": "entry",
"coreJs": "3.37"
}
}Configurable level of aggressiveness⬆
By default, core-js sets polyfills only when they are required. That means that core-js checks if a feature is available and works correctly or not and if it has no problems, core-js use native implementation.
But sometimes core-js feature detection could be too strict for your case. For example, Promise constructor requires the support of unhandled rejection tracking and @@species.
Sometimes we could have inverse problem - knowingly broken environment with problems not covered by core-js feature detection.
For those cases, we could redefine this behaviour for certain polyfills:
const configurator = require('core-js/configurator');
configurator({
useNative: ['Promise'], // polyfills will be used only if natives completely unavailable
usePolyfill: ['Array.from', 'String.prototype.padEnd'], // polyfills will be used anyway
useFeatureDetection: ['Map', 'Set'], // default behaviour
});
require('core-js/actual');It does not work with some features. Also, if you change the default behaviour, even core-js internals may not work correctly.
Custom build⬆
For some cases could be useful to exclude some core-js features or generate a polyfill for target engines. You could use core-js-builder package for that.
Supported engines and compatibility data⬆
core-js tries to support all possible JS engines and environments with ES3 support. Some features have a higher lower bar - for example, some accessors can properly work only from ES5, promises require a way to set a microtask or a task, etc.
However, I have no possibility to test core-js absolutely everywhere - for example, testing in IE7- and some other ancient was stopped. The list of definitely supported engines you can see in the compatibility table by the link below. Write if you have issues or questions with the support of any engine.
core-js project provides (as core-js-compat package) all required data about the necessity of core-js modules, entry points, and tools for work with it - it's useful for integration with tools like babel or swc. If you wanna help, you could take a look at the related section of CONTRIBUTING.md. The visualization of compatibility data and the browser tests runner is available here, the example:
Features:⬆
core-js(-pure)
ECMAScript⬆
core-js(-pure)/es
ECMAScript: Object⬆
Modules es.object.assign, es.object.create, es.object.define-getter, es.object.define-property, es.object.define-properties, es.object.define-setter, es.object.entries, es.object.freeze, es.object.from-entries, es.object.get-own-property-descriptor, es.object.get-own-property-descriptors, es.object.get-own-property-names, es.object.get-prototype-of, es.object.group-by, es.object.has-own, es.object.is, es.object.is-extensible, es.object.is-frozen, es.object.is-sealed, es.object.keys, es.object.lookup-setter, es.object.lookup-getter, es.object.prevent-extensions, es.object.proto, es.object.to-string, es.object.seal, es.object.set-prototype-of, es.object.values.
class Object {
toString(): string; // ES2015+ fix: @@toStringTag support
__defineGetter__(property: PropertyKey, getter: Function): void;
__defineSetter__(property: PropertyKey, setter: Function): void;
__lookupGetter__(property: PropertyKey): Function | void;
__lookupSetter__(property: PropertyKey): Function | void;
__proto__: Object | null; // required a way setting of prototype - will not in IE10-, it's for modern engines like Deno
static assign(target: Object, ...sources: Array<Object>): Object;
static create(prototype: Object | null, properties?: { [property: PropertyKey]: PropertyDescriptor }): Object;
static defineProperties(object: Object, properties: { [property: PropertyKey]: PropertyDescriptor })): Object;
static defineProperty(object: Object, property: PropertyKey, attributes: PropertyDescriptor): Object;
static entries(object: Object): Array<[string, mixed]>;
static freeze(object: any): any;
static fromEntries(iterable: Iterable<[key, value]>): Object;
static getOwnPropertyDescriptor(object: any, property: PropertyKey): PropertyDescriptor | void;
static getOwnPropertyDescriptors(object: any): { [property: PropertyKey]: PropertyDescriptor };
static getOwnPropertyNames(object: any): Array<string>;
static getPrototypeOf(object: any): Object | null;
static groupBy(items: Iterable, callbackfn: (value: any, index: number) => key): { [key]: Array<mixed> };
static hasOwn(object: object, key: PropertyKey): boolean;
static is(value1: any, value2: any): boolean;
static isExtensible(object: any): boolean;
static isFrozen(object: any): boolean;
static isSealed(object: any): boolean;
static keys(object: any): Array<string>;
static preventExtensions(object: any): any;
static seal(object: any): any;
static setPrototypeOf(target: any, prototype: Object | null): any; // required __proto__ - IE11+
static values(object: any): Array<mixed>;
}core-js(-pure)/es|stable|actual|full/object
core-js(-pure)/es|stable|actual|full/object/assign
core-js(-pure)/es|stable|actual|full/object/is
core-js(-pure)/es|stable|actual|full/object/set-prototype-of
core-js(-pure)/es|stable|actual|full/object/get-prototype-of
core-js(-pure)/es|stable|actual|full/object/create
core-js(-pure)/es|stable|actual|full/object/define-property
core-js(-pure)/es|stable|actual|full/object/define-properties
core-js(-pure)/es|stable|actual|full/object/get-own-property-descriptor
core-js(-pure)/es|stable|actual|full/object/get-own-property-descriptors
core-js(-pure)/es|stable|actual|full/object/group-by
core-js(-pure)/es|stable|actual|full/object/has-own
core-js(-pure)/es|stable|actual|full/object/keys
core-js(-pure)/es|stable|actual|full/object/values
core-js(-pure)/es|stable|actual|full/object/entries
core-js(-pure)/es|stable|actual|full/object/get-own-property-names
core-js(-pure)/es|stable|actual|full/object/freeze
core-js(-pure)/es|stable|actual|full/object/from-entries
core-js(-pure)/es|stable|actual|full/object/seal
core-js(-pure)/es|stable|actual|full/object/prevent-extensions
core-js/es|stable|actual|full/object/proto
core-js(-pure)/es|stable|actual|full/object/is-frozen
core-js(-pure)/es|stable|actual|full/object/is-sealed
core-js(-pure)/es|stable|actual|full/object/is-extensible
core-js/es|stable|actual|full/object/to-string
core-js(-pure)/es|stable|actual|full/object/define-getter
core-js(-pure)/es|stable|actual|full/object/define-setter
core-js(-pure)/es|stable|actual|full/object/lookup-getter
core-js(-pure)/es|stable|actual|full/object/lookup-setter
Examples:
let foo = { q: 1, w: 2 };
let bar = { e: 3, r: 4 };
let 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
let object = {
[Symbol.toStringTag]: 'Foo'
};
'' + object; // => '[object Foo]'
Object.keys('qwe'); // => ['0', '1', '2']
Object.getPrototypeOf('qwe') === String.prototype; // => true
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
}
// Shallow object cloning with prototype and descriptors:
let copy = Object.create(Object.getPrototypeOf(object), Object.getOwnPropertyDescriptors(object));
// Mixin:
Object.defineProperties(target, Object.getOwnPropertyDescriptors(source));
const map = new Map([['a', 1], ['b', 2]]);
Object.fromEntries(map); // => { a: 1, b: 2 }
class Unit {
constructor(id) {
this.id = id;
}
toString() {
return `unit${ this.id }`;
}
}
const units = new Set([new Unit(101), new Unit(102)]);
Object.fromEntries(units.entries()); // => { unit101: Unit { id: 101 }, unit102: Unit { id: 102 } }
Object.hasOwn({ foo: 42 }, 'foo'); // => true
Object.hasOwn({ foo: 42 }, 'bar'); // => false
Object.hasOwn({}, 'toString'); // => false
Object.groupBy([1, 2, 3, 4, 5], it => it % 2); // => { 1: [1, 3, 5], 0: [2, 4] }ECMAScript: Function⬆
Modules es.function.name, es.function.has-instance. Just ES5: es.function.bind.
class Function {
name: string;
bind(thisArg: any, ...args: Array<mixed>): Function;
@@hasInstance(value: any): boolean;
}core-js/es|stable|actual|full/function
core-js/es|stable|actual|full/function/name
core-js/es|stable|actual|full/function/has-instance
core-js(-pure)/es|stable|actual|full/function/bind
core-js(-pure)/es|stable|actual|full/function/virtual/bind
(function foo() {}).name // => 'foo'
console.log.bind(console, 42)(43); // => 42 43ECMAScript: Error⬆
Modules es.aggregate-error, es.aggregate-error.cause, es.error.cause, es.error.to-string.
class [
Error,
EvalError,
RangeError,
ReferenceError,
SyntaxError,
TypeError,
URIError,
WebAssembly.CompileError,
WebAssembly.LinkError,
WebAssembly.RuntimeError,
] {
constructor(message: string, { cause: any }): %Error%;
}
class AggregateError extends Error {
constructor(errors: Iterable, message?: string, { cause: any }?): AggregateError;
errors: Array<any>;
message: string;
cause: any;
}
class Error {
toString(): string; // different fixes
}core-js(-pure)/es|stable|actual|full/aggregate-error
core-js/es|stable|actual|full/error
core-js/es|stable|actual|full/error/constructor
core-js/es|stable|actual|full/error/to-string
const error1 = new TypeError('Error 1');
const error2 = new TypeError('Error 2');
const aggregate = new AggregateError([error1, error2], 'Collected errors');
aggregate.errors[0] === error1; // => true
aggregate.errors[1] === error2; // => true
const cause = new TypeError('Something wrong');
const error = new TypeError('Here explained what`s wrong', { cause });
error.cause === cause; // => true
Error.prototype.toString.call({ message: 1, name: 2 }) === '2: 1'; // => trueECMAScript: Array⬆
Modules es.array.from, es.array.is-array, es.array.of, es.array.copy-within, es.array.fill, es.array.find, es.array.find-index, es.array.find-last, es.array.find-last-index, es.array.iterator, es.array.includes, es.array.push, es.array.slice, es.array.join, es.array.unshift, es.array.index-of, es.array.last-index-of, es.array.every, es.array.some, es.array.for-each, es.array.map, es.array.filter, es.array.reduce, es.array.reduce-right, es.array.reverse, es.array.sort, es.array.flat, es.array.flat-map, es.array.unscopables.flat, es.array.unscopables.flat-map, es.array.at, es.array.to-reversed, es.array.to-sorted, es.array.to-spliced, es.array.with.
class Array {
at(index: int): any;
concat(...args: Array<mixed>): Array<mixed>; // with adding support of @@isConcatSpreadable and @@species
copyWithin(target: number, start: number, end?: number): this;
entries(): Iterator<[index, value]>;
every(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): boolean;
fill(value: any, start?: number, end?: number): this;
filter(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): Array<mixed>; // with adding support of @@species
find(callbackfn: (value: any, index: number, target: any) => boolean), thisArg?: any): any;
findIndex(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): uint;
findLast(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): any;
findLastIndex(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): uint;
flat(depthArg?: number = 1): Array<mixed>;
flatMap(mapFn: (value: any, index: number, target: any) => any, thisArg: any): Array<mixed>;
forEach(callbackfn: (value: any, index: number, target: any) => void, thisArg?: any): void;
includes(searchElement: any, from?: number): boolean;
indexOf(searchElement: any, from?: number): number;
join(separator: string = ','): string;
keys(): Iterator<index>;
lastIndexOf(searchElement: any, from?: number): number;
map(mapFn: (value: any, index: number, target: any) => any, thisArg?: any): Array<mixed>; // with adding support of @@species
push(...args: Array<mixed>): uint;
reduce(callbackfn: (memo: any, value: any, index: number, target: any) => any, initialValue?: any): any;
reduceRight(callbackfn: (memo: any, value: any, index: number, target: any) => any, initialValue?: any): any;
reverse(): this; // Safari 12.0 bug fix
slice(start?: number, end?: number): Array<mixed>; // with adding support of @@species
splice(start?: number, deleteCount?: number, ...items: Array<mixed>): Array<mixed>; // with adding support of @@species
some(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): boolean;
sort(comparefn?: (a: any, b: any) => number): this; // with modern behavior like stable sort
toReversed(): Array<mixed>;
toSpliced(start?: number, deleteCount?: number, ...items: Array<mixed>): Array<mixed>;
toSorted(comparefn?: (a: any, b: any) => number): Array<mixed>;
unshift(...args: Array<mixed>): uint;
values(): Iterator<value>;
with(index: includes, value: any): Array<mixed>;
@@iterator(): Iterator<value>;
@@unscopables: { [newMethodNames: string]: true };
static from(items: Iterable | ArrayLike, mapFn?: (value: any, index: number) => any, thisArg?: any): Array<mixed>;
static isArray(value: any): boolean;
static of(...args: Array<mixed>): Array<mixed>;
}
class Arguments {
@@iterator(): Iterator<value>; // available only in core-js methods
}core-js(-pure)/es|stable|actual|full/array
core-js(-pure)/es|stable|actual|full/array/from
core-js(-pure)/es|stable|actual|full/array/of
core-js(-pure)/es|stable|actual|full/array/is-array
core-js(-pure)/es|stable|actual|full/array(/virtual)/at
core-js(-pure)/es|stable|actual|full/array(/virtual)/concat
core-js(-pure)/es|stable|actual|full/array(/virtual)/copy-within
core-js(-pure)/es|stable|actual|full/array(/virtual)/entries
core-js(-pure)/es|stable|actual|full/array(/virtual)/every
core-js(-pure)/es|stable|actual|full/array(/virtual)/fill
core-js(-pure)/es|stable|actual|full/array(/virtual)/filter
core-js(-pure)/es|stable|actual|full/array(/virtual)/find
core-js(-pure)/es|stable|actual|full/array(/virtual)/find-index
core-js(-pure)/es|stable|actual|full/array(/virtual)/find-last
core-js(-pure)/es|stable|actual|full/array(/virtual)/find-last-index
core-js(-pure)/es|stable|actual|full/array(/virtual)/flat
core-js(-pure)/es|stable|actual|full/array(/virtual)/flat-map
core-js(-pure)/es|stable|actual|full/array(/virtual)/for-each
core-js(-pure)/es|stable|actual|full/array(/virtual)/includes
core-js(-pure)/es|stable|actual|full/array(/virtual)/index-of
core-js(-pure)/es|stable|actual|full/array(/virtual)/iterator
core-js(-pure)/es|stable|actual|full/array(/virtual)/join
core-js(-pure)/es|stable|actual|full/array(/virtual)/keys
core-js(-pure)/es|stable|actual|full/array(/virtual)/last-index-of
core-js(-pure)/es|stable|actual|full/array(/virtual)/map
core-js(-pure)/es|stable|actual|full/array(/virtual)/push
core-js(-pure)/es|stable|actual|full/array(/virtual)/reduce
core-js(-pure)/es|stable|actual|full/array(/virtual)/reduce-right
core-js(-pure)/es|stable|actual|full/array(/virtual)/reverse
core-js(-pure)/es|stable|actual|full/array(/virtual)/slice
core-js(-pure)/es|stable|actual|full/array(/virtual)/some
core-js(-pure)/es|stable|actual|full/array(/virtual)/sort
core-js(-pure)/es|stable|actual|full/array(/virtual)/splice
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-reversed
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-sorted
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-spliced
core-js(-pure)/es|stable|actual|full/array(/virtual)/unshift
core-js(-pure)/es|stable|actual|full/array(/virtual)/values
core-js(-pure)/es|stable|actual|full/array(/virtual)/with
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', it => it * it); // => [1, 4, 9]
Array.of(1); // => [1]
Array.of(1, 2, 3); // => [1, 2, 3]
let array = ['a', 'b', 'c'];
for (let value of array) console.log(value); // => 'a', 'b', 'c'
for (let value of array.values()) console.log(value); // => 'a', 'b', 'c'
for (let key of array.keys()) console.log(key); // => 0, 1, 2
for (let [key, value] of array.entries()) {
console.log(key); // => 0, 1, 2
console.log(value); // => 'a', 'b', 'c'
}
function isOdd(value) {
return value % 2;
}
[4, 8, 15, 16, 23, 42].find(isOdd); // => 15
[4, 8, 15, 16, 23, 42].findIndex(isOdd); // => 2
[1, 2, 3, 4].findLast(isOdd); // => 3
[1, 2, 3, 4].findLastIndex(isOdd); // => 2
Array(5).fill(42); // => [42, 42, 42, 42, 42]
[1, 2, 3, 4, 5].copyWithin(0, 3); // => [4, 5, 3, 4, 5]
[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
[1, [2, 3], [4, 5]].flat(); // => [1, 2, 3, 4, 5]
[1, [2, [3, [4]]], 5].flat(); // => [1, 2, [3, [4]], 5]
[1, [2, [3, [4]]], 5].flat(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]
[1, 2, 3].at(1); // => 2
[1, 2, 3].at(-1); // => 3
const sequence = [1, 2, 3];
sequence.toReversed(); // => [3, 2, 1]
sequence; // => [1, 2, 3]
const array = [1, 2, 3, 4];
array.toSpliced(1, 2, 5, 6, 7); // => [1, 5, 6, 7, 4]
array; // => [1, 2, 3, 4]
const outOfOrder = [3, 1, 2];
outOfOrder.toSorted(); // => [1, 2, 3]
outOfOrder; // => [3, 1, 2]
const correctionNeeded = [1, 1, 3];
correctionNeeded.with(1, 2); // => [1, 2, 3]
correctionNeeded; // => [1, 1, 3]ECMAScript: String and RegExp⬆
The main part of String features: modules es.string.from-code-point, es.string.raw, es.string.iterator, es.string.split, es.string.code-point-at, es.string.ends-with, es.string.includes, es.string.repeat, es.string.pad-start, es.string.pad-end, es.string.starts-with, es.string.trim, es.string.trim-start, es.string.trim-end, es.string.match-all, es.string.replace-all, es.string.at-alternative, es.string.is-well-formed, es.string.to-well-formed.
Adding support of well-known symbols @@match, @@replace, @@search and @@split and direct .exec calls to related String methods, modules es.string.match, es.string.replace, es.string.search and es.string.split.
Annex B methods. Modules es.string.anchor, es.string.big, es.string.blink, es.string.bold, es.string.fixed, es.string.fontcolor, es.string.fontsize, es.string.italics, es.string.link, es.string.small, es.string.strike, es.string.sub, es.string.sup, es.string.substr, es.escape and es.unescape.
RegExp features: modules es.regexp.constructor, es.regexp.dot-all, es.regexp.flags, es.regexp.sticky and es.regexp.test.
class String {
static fromCodePoint(...codePoints: Array<number>): string;
static raw({ raw: Array<string> }, ...substitutions: Array<string>): string;
at(index: int): string;
includes(searchString: string, position?: number): boolean;
startsWith(searchString: string, position?: number): boolean;
endsWith(searchString: string, position?: number): boolean;
repeat(count: number): string;
padStart(length: number, fillStr?: string = ' '): string;
padEnd(length: number, fillStr?: string = ' '): string;
codePointAt(pos: number): number | void;
match(template: any): any; // ES2015+ fix for support @@match
matchAll(regexp: RegExp): Iterator;
replace(template: any, replacer: any): any; // ES2015+ fix for support @@replace
replaceAll(searchValue: string | RegExp, replaceString: string | (searchValue, index, this) => string): string;
search(template: any): any; // ES2015+ fix for support @@search
split(template: any, limit?: int): Array<string>;; // ES2015+ fix for support @@split, some fixes for old engines
trim(): string;
trimLeft(): string;
trimRight(): string;
trimStart(): string;
trimEnd(): string;
isWellFormed(): boolean;
toWellFormed(): string;
anchor(name: string): string;
big(): string;
blink(): string;
bold(): string;
fixed(): string;
fontcolor(color: string): string;
fontsize(size: any): string;
italics(): string;
link(url: string): string;
small(): string;
strike(): string;
sub(): string;
substr(start: int, length?: int): string;
sup(): string;
@@iterator(): Iterator<characters>;
}
class RegExp {
// support of sticky (`y`) flag, dotAll (`s`) flag, named capture groups, can alter flags
constructor(pattern: RegExp | string, flags?: string): RegExp;
exec(): Array<string | undefined> | null; // IE8 fixes
test(string: string): boolean; // delegation to `.exec`
toString(): string; // ES2015+ fix - generic
@@match(string: string): Array | null;
@@matchAll(string: string): Iterator;
@@replace(string: string, replaceValue: Function | string): string;
@@search(string: string): number;
@@split(string: string, limit: number): Array<string>;
readonly attribute dotAll: boolean; // IE9+
readonly attribute flags: string; // IE9+
readonly attribute sticky: boolean; // IE9+
}
function escape(string: string): string;
function unescape(string: string): string;core-js(-pure)/es|stable|actual|full/string
core-js(-pure)/es|stable|actual|full/string/from-code-point
core-js(-pure)/es|stable|actual|full/string/raw
core-js/es|stable|actual|full/string/match
core-js/es|stable|actual|full/string/replace
core-js/es|stable|actual|full/string/search
core-js/es|stable|actual|full/string/split
core-js(-pure)/es|stable|actual/string(/virtual)/at
core-js(-pure)/es|stable|actual|full/string(/virtual)/code-point-at
core-js(-pure)/es|stable|actual|full/string(/virtual)/ends-with
core-js(-pure)/es|stable|actual|full/string(/virtual)/includes
core-js(-pure)/es|stable|actual|full/string(/virtual)/starts-with
core-js(-pure)/es|stable|actual|full/string(/virtual)/match-all
core-js(-pure)/es|stable|actual|full/string(/virtual)/pad-start
core-js(-pure)/es|stable|actual|full/string(/virtual)/pad-end
core-js(-pure)/es|stable|actual|full/string(/virtual)/repeat
core-js(-pure)/es|stable|actual|full/string(/virtual)/replace-all
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-start
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-end
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-left
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-right
core-js(-pure)/es|stable|actual|full/string(/virtual)/is-well-formed
core-js(-pure)/es|stable|actual|full/string(/virtual)/to-well-formed
core-js(-pure)/es|stable|actual|full/string(/virtual)/anchor
core-js(-pure)/es|stable|actual|full/string(/virtual)/big
core-js(-pure)/es|stable|actual|full/string(/virtual)/blink
core-js(-pure)/es|stable|actual|full/string(/virtual)/bold
core-js(-pure)/es|stable|actual|full/string(/virtual)/fixed
core-js(-pure)/es|stable|actual|full/string(/virtual)/fontcolor
core-js(-pure)/es|stable|actual|full/string(/virtual)/fontsize
core-js(-pure)/es|stable|actual|full/string(/virtual)/italics
core-js(-pure)/es|stable|actual|full/string(/virtual)/link
core-js(-pure)/es|stable|actual|full/string(/virtual)/small
core-js(-pure)/es|stable|actual|full/string(/virtual)/strike
core-js(-pure)/es|stable|actual|full/string(/virtual)/sub
core-js(-pure)/es|stable|actual|full/string(/virtual)/substr
core-js(-pure)/es|stable|actual|full/string(/virtual)/sup
core-js(-pure)/es|stable|actual|full/string(/virtual)/iterator
core-js/es|stable|actual|full/regexp
core-js/es|stable|actual|full/regexp/constructor
core-js/es|stable|actual|full/regexp/dot-all
core-js(-pure)/es|stable|actual|full/regexp/flags
core-js/es|stable|actual|full/regexp/sticky
core-js/es|stable|actual|full/regexp/test
core-js/es|stable|actual|full/regexp/to-string
core-js/es|stable|actual|full/escape
core-js/es|stable|actual|full/unescape
for (let value of 'a𠮷b') {
console.log(value); // => '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'
'hello'.padStart(10); // => ' hello'
'hello'.padStart(10, '1234'); // => '12341hello'
'hello'.padEnd(10); // => 'hello '
'hello'.padEnd(10, '1234'); // => 'hello12341'
'𠮷'.codePointAt(0); // => 134071
String.fromCodePoint(97, 134071, 98); // => 'a𠮷b'
let name = 'Bob';
String.raw`Hi\n${name}!`; // => 'Hi\\nBob!' (ES2015 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('https://example.com'); // => '<a href="https://example.com">baz</a>'
RegExp('.', 's').test('\n'); // => true
RegExp('.', 's').dotAll; // => true
RegExp('foo:(?<foo>\\w+),bar:(?<bar>\\w+)').exec('foo:abc,bar:def').groups.bar; // => 'def'
'foo:abc,bar:def'.replace(RegExp('foo:(?<foo>\\w+),bar:(?<bar>\\w+)'), '$<bar>,$<foo>'); // => 'def,abc'
RegExp(/./g, 'm'); // => /./m
/foo/.flags; // => ''
/foo/gim.flags; // => 'gim'
RegExp('foo', 'y').sticky; // => true
const text = 'First line\nSecond line';
const regex = RegExp('(\\S+) line\\n?', 'y');
regex.exec(text)[1]; // => 'First'
regex.exec(text)[1]; // => 'Second'
regex.exec(text); // => null
'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'
' hello '.trimLeft(); // => 'hello '
' hello '.trimRight(); // => ' hello'
' hello '.trimStart(); // => 'hello '
' hello '.trimEnd(); // => ' hello'
for (let [_, d, D] of '1111a2b3cccc'.matchAll(/(\d)(\D)/g)) {
console.log(d, D); // => 1 a, 2 b, 3 c
}
'Test abc test test abc test.'.replaceAll('abc', 'foo'); // -> 'Test foo test test foo test.'
'abc'.at(1); // => 'b'
'abc'.at(-1); // => 'c'
'a💩b'.isWellFormed(); // => true
'a\uD83Db'.isWellFormed(); // => false
'a💩b'.toWellFormed(); // => 'a💩b'
'a\uD83Db'.toWellFormed(); // => 'a�b'ECMAScript: Number⬆
Module es.number.constructor. Number constructor support binary and octal literals, example:
Number('0b1010101'); // => 85
Number('0o7654321'); // => 2054353Modules es.number.epsilon, es.number.is-finite, es.number.is-integer, es.number.is-nan, es.number.is-safe-integer, es.number.max-safe-integer, es.number.min-safe-integer, es.number.parse-float, es.number.parse-int, es.number.to-exponential, es.number.to-fixed, es.number.to-precision, es.parse-int, es.parse-float.
class Number {
constructor(value: any): number;
toExponential(digits: number): string;
toFixed(digits: number): string;
toPrecision(precision: number): string;
static isFinite(number: any): boolean;
static isNaN(number: any): boolean;
static isInteger(number: any): boolean;
static isSafeInteger(number: any): boolean;
static parseFloat(string: string): number;
static parseInt(string: string, radix?: number = 10): number;
static EPSILON: number;
static MAX_SAFE_INTEGER: number;
static MIN_SAFE_INTEGER: number;
}
function parseFloat(string: string): number;
function parseInt(string: string, radix?: number = 10): number;core-js(-pure)/es|stable|actual|full/number
core-js(-pure)/es|stable|actual|full/number/constructor
core-js(-pure)/es|stable|actual|full/number/is-finite
core-js(-pure)/es|stable|actual|full/number/is-nan
core-js(-pure)/es|stable|actual|full/number/is-integer
core-js(-pure)/es|stable|actual|full/number/is-safe-integer
core-js(-pure)/es|stable|actual|full/number/parse-float
core-js(-pure)/es|stable|actual|full/number/parse-int
core-js(-pure)/es|stable|actual|full/number/epsilon
core-js(-pure)/es|stable|actual|full/number/max-safe-integer
core-js(-pure)/es|stable|actual|full/number/min-safe-integer
core-js(-pure)/es|stable|actual|full/number(/virtual)/to-exponential
core-js(-pure)/es|stable|actual|full/number(/virtual)/to-fixed
core-js(-pure)/es|stable|actual|full/number(/virtual)/to-precision
core-js(-pure)/es|stable|actual|full/parse-float
core-js(-pure)/es|stable|actual|full/parse-int
ECMAScript: Math⬆
Modules es.math.acosh, es.math.asinh, es.math.atanh, es.math.cbrt, es.math.clz32, es.math.cosh, es.math.expm1, es.math.fround, es.math.hypot, es.math.imul, es.math.log10, es.math.log1p, es.math.log2, es.math.sign, es.math.sinh, es.math.tanh, es.math.trunc.
namespace Math {
acosh(number: number): number;
asinh(number: number): number;
atanh(number: number): number;
cbrt(number: number): number;
clz32(number: number): number;
cosh(number: number): number;
expm1(number: number): number;
fround(number: number): number;
hypot(...args: Array<number>): number;
imul(number1: number, number2: number): number;
log1p(number: number): number;
log10(number: number): number;
log2(number: number): number;
sign(number: number): 1 | -1 | 0 | -0 | NaN;
sinh(number: number): number;
tanh(number: number): number;
trunc(number: number): number;
}core-js(-pure)/es|stable|actual|full/math
core-js(-pure)/es|stable|actual|full/math/acosh
core-js(-pure)/es|stable|actual|full/math/asinh
core-js(-pure)/es|stable|actual|full/math/atanh
core-js(-pure)/es|stable|actual|full/math/cbrt
core-js(-pure)/es|stable|actual|full/math/clz32
core-js(-pure)/es|stable|actual|full/math/cosh
core-js(-pure)/es|stable|actual|full/math/expm1
core-js(-pure)/es|stable|actual|full/math/fround
core-js(-pure)/es|stable|actual|full/math/hypot
core-js(-pure)/es|stable|actual|full/math/imul
core-js(-pure)/es|stable|actual|full/math/log1p
core-js(-pure)/es|stable|actual|full/math/log10
core-js(-pure)/es|stable|actual|full/math/log2
core-js(-pure)/es|stable|actual|full/math/sign
core-js(-pure)/es|stable|actual|full/math/sinh
core-js(-pure)/es|stable|actual|full/math/tanh
core-js(-pure)/es|stable|actual|full/math/trunc
ECMAScript: Date⬆
Modules es.date.to-string, ES5 features with fixes: es.date.now, es.date.to-iso-string, es.date.to-json and es.date.to-primitive.
Annex B methods. Modules es.date.get-year, es.date.set-year and es.date.to-gmt-string.
class Date {
getYear(): int;
setYear(year: int): number;
toGMTString(): string;
toISOString(): string;
toJSON(): string;
toString(): string;
@@toPrimitive(hint: 'default' | 'number' | 'string'): string | number;
static now(): number;
}core-js/es|stable|actual|full/date
core-js/es|stable|actual|full/date/to-string
core-js(-pure)/es|stable|actual|full/date/now
core-js(-pure)/es|stable|actual|full/date/get-year
core-js(-pure)/es|stable|actual|full/date/set-year
core-js(-pure)/es|stable|actual|full/date/to-gmt-string
core-js(-pure)/es|stable|actual|full/date/to-iso-string
core-js(-pure)/es|stable|actual|full/date/to-json
core-js(-pure)/es|stable|actual|full/date/to-primitive
new Date(NaN).toString(); // => 'Invalid Date'ECMAScript: Promise⬆
Modules es.promise, es.promise.all-settled, es.promise.any, es.promise.finally and es.promise.with-resolvers.
class Promise {
constructor(executor: (resolve: Function, reject: Function) => void): Promise;
then(onFulfilled: Function, onRejected: Function): Promise;
catch(onRejected: Function): Promise;
finally(onFinally: Function): Promise;
static all(iterable: Iterable): Promise;
static allSettled(iterable: Iterable): Promise;
static any(promises: Iterable): Promise;
static race(iterable: Iterable): Promise;
static reject(r: any): Promise;
static resolve(x: any): Promise;
static withResolvers(): { promise: Promise, resolve: function, reject: function };
}core-js(-pure)/es|stable|actual|full/promise
core-js(-pure)/es|stable|actual|full/promise/all-settled
core-js(-pure)/es|stable|actual|full/promise/any
core-js(-pure)/es|stable|actual|full/promise/finally
core-js(-pure)/es|stable|actual|full/promise/with-resolvers
Basic example:
function sleepRandom(time) {
return new Promise((resolve, reject) => {
setTimeout(resolve, time * 1e3, 0 | Math.random() * 1e3);
});
}
console.log('Run'); // => Run
sleepRandom(5).then(result => {
console.log(result); // => 869, after 5 sec.
return sleepRandom(10);
}).then(result => {
console.log(result); // => 202, after 10 sec.
}).then(() => {
console.log('immediately after'); // => immediately after
throw Error('Irror!');
}).then(() => {
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')); // => ES promisePromise#finally example:
Promise.resolve(42).finally(() => console.log('You will see it anyway'));
Promise.reject(42).finally(() => console.log('You will see it anyway'));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((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 secPromise.allSettled example:
Promise.allSettled([
Promise.resolve(1),
Promise.reject(2),
Promise.resolve(3),
]).then(console.log); // => [{ value: 1, status: 'fulfilled' }, { reason: 2, status: 'rejected' }, { value: 3, status: 'fulfilled' }]Promise.any example:
Promise.any([
Promise.resolve(1),
Promise.reject(2),
Promise.resolve(3),
]).then(console.log); // => 1
Promise.any([
Promise.reject(1),
Promise.reject(2),
Promise.reject(3),
]).catch(({ errors }) => console.log(errors)); // => [1, 2, 3]Promise.withResolvers examples:
const d = Promise.withResolvers();
d.resolve(42);
d.promise.then(console.log); // => 42Example with async functions:
let 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.
let [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, 'Error!');
console.log('Will not be displayed');
} catch (e) {
console.log(e); // => Error: 'Error!', after 5 sec.
}
})();Unhandled rejection tracking⬆
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));
let promise = Promise.reject(42);
// unhandled 42 [object Promise]
setTimeout(() => promise.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.addEventListener('unhandledrejection', e => console.log('unhandled', e.reason, e.promise));
window.addEventListener('rejectionhandled', e => console.log('handled', e.reason, e.promise));
// or
window.onunhandledrejection = e => console.log('unhandled', e.reason, e.promise);
window.onrejectionhandled = e => console.log('handled', e.reason, e.promise);
let promise = Promise.reject(42);
// => unhandled 42 [object Promise]
setTimeout(() => promise.catch(() => {}), 1e3);
// => handled 42 [object Promise]ECMAScript: Symbol⬆
Modules es.symbol, es.symbol.async-iterator, es.symbol.description, es.symbol.has-instance, es.symbol.is-concat-spreadable, es.symbol.iterator, es.symbol.match, es.symbol.replace, es.symbol.search, es.symbol.species, es.symbol.split, es.symbol.to-primitive, es.symbol.to-string-tag, es.symbol.unscopables, es.math.to-string-tag.
class Symbol {
constructor(description?): symbol;
readonly attribute description: string | void;
static asyncIterator: @@asyncIterator;
static hasInstance: @@hasInstance;
static isConcatSpreadable: @@isConcatSpreadable;
static iterator: @@iterator;
static match: @@match;
static replace: @@replace;
static search: @@search;
static species: @@species;
static split: @@split;
static toPrimitive: @@toPrimitive;
static toStringTag: @@toStringTag;
static unscopables: @@unscopables;
static for(key: string): symbol;
static keyFor(sym: symbol): string;
static useSimple(): void;
static useSetter(): void;
}
class Object {
static getOwnPropertySymbols(object: any): Array<symbol>;
}Also wrapped some methods for correct work with Symbol polyfill.
class Object {
static create(prototype: Object | null, properties?: { [property: PropertyKey]: PropertyDescriptor }): Object;
static defineProperties(object: Object, properties: { [property: PropertyKey]: PropertyDescriptor })): Object;
static defineProperty(object: Object, property: PropertyKey, attributes: PropertyDescriptor): Object;
static getOwnPropertyDescriptor(object: any, property: PropertyKey): PropertyDescriptor | void;
static getOwnPropertyNames(object: any): Array<string>;
propertyIsEnumerable(key: PropertyKey): boolean;
}core-js(-pure)/es|stable|actual|full/symbol
core-js(-pure)/es|stable|actual|full/symbol/async-iterator
core-js/es|stable|actual|full/symbol/description
core-js(-pure)/es|stable|actual|full/symbol/has-instance
core-js(-pure)/es|stable|actual|full/symbol/is-concat-spreadable
core-js(-pure)/es|stable|actual|full/symbol/iterator
core-js(-pure)/es|stable|actual|full/symbol/match
core-js(-pure)/es|stable|actual|full/symbol/replace
core-js(-pure)/es|stable|actual|full/symbol/search
core-js(-pure)/es|stable|actual|full/symbol/species
core-js(-pure)/es|stable|actual|full/symbol/split
core-js(-pure)/es|stable|actual|full/symbol/to-primitive
core-js(-pure)/es|stable|actual|full/symbol/to-string-tag
core-js(-pure)/es|stable|actual|full/symbol/unscopables
core-js(-pure)/es|stable|actual|full/symbol/for
core-js(-pure)/es|stable|actual|full/symbol/key-for
core-js(-pure)/es|stable|actual|full/object/get-own-property-symbols
core-js(-pure)/es|stable|actual|full/math/to-string-tag
let Person = (() => {
let NAME = Symbol('name');
return class {
constructor(name) {
this[NAME] = name;
}
getName() {
return this[NAME];
}
}
})();
let person = new Person('Vasya');
console.log(person.getName()); // => 'Vasya'
console.log(person['name']); // => undefined
console.log(person[Symbol('name')]); // => undefined, symbols are uniq
for (let key in person) console.log(key); // => nothing, symbols are not enumerableSymbol.for & Symbol.keyFor example:
let symbol = Symbol.for('key');
symbol === Symbol.for('key'); // true
Symbol.keyFor(symbol); // 'key'Example with methods for getting own object keys:
let object = { a: 1 };
Object.defineProperty(object, 'b', { value: 2 });
object[Symbol('c')] = 3;
Object.keys(object); // => ['a']
Object.getOwnPropertyNames(object); // => ['a', 'b']
Object.getOwnPropertySymbols(object); // => [Symbol(c)]
Reflect.ownKeys(object); // => ['a', 'b', Symbol(c)]Symbol('foo').description; // => 'foo'
Symbol().description; // => undefinedCaveats when using Symbol polyfill:⬆
- We can't add new primitive type,
Symbolreturns object. Symbol.forandSymbol.keyForcan't be polyfilled cross-realm.- By default, to hide the keys,
Symbolpolyfill defines setter inObject.prototype. For this reason, uncontrolled creation of symbols can cause memory leak and theinoperator is not working correctly withSymbolpolyfill:Symbol() in {} // => true.
You can disable defining setters in Object.prototype. Example:
Symbol.useSimple();
let symbol1 = Symbol('symbol1');
let object1 = {};
object1[symbol1] = true;
for (let key in object1) console.log(key); // => 'Symbol(symbol1)_t.qamkg9f3q', w/o native Symbol
Symbol.useSetter();
let symbol2 = Symbol('symbol2');
let object2 = {};
object2[symbol2] = true;
for (let key in object2) 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, IE
localStorage).
ECMAScript: Collections⬆
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).
Map⬆
Modules es.map and es.map.group-by.
class Map {
constructor(iterable?: Iterable<[key, value]>): Map;
clear(): void;
delete(key: any): boolean;
forEach(callbackfn: (value: any, key: any, target: any) => void, thisArg: any): void;
get(key: any): any;
has(key: any): boolean;
set(key: any, val: any): this;
values(): Iterator<value>;
keys(): Iterator<key>;
entries(): Iterator<[key, value]>;
@@iterator(): Iterator<[key, value]>;
readonly attribute size: number;
static groupBy(items: Iterable, callbackfn: (value: any, index: number) => key): Map<key, Array<mixed>>;
}core-js(-pure)/es|stable|actual|full/map
core-js(-pure)/es|stable|actual|full/map/group-by
let array = [1];
let map = new Map([['a', 1], [42, 2]]);
map.set(array, 3).set(true, 4);
console.log(map.size); // => 4
console.log(map.has(array)); // => true
console.log(map.has([1])); // => false
console.log(map.get(array)); // => 3
map.forEach((val, key) => {
console.log(val); // => 1, 2, 3, 4
console.log(key); // => 'a', 42, [1], true
});
map.delete(array);
console.log(map.size); // => 3
console.log(map.get(array)); // => undefined
console.log(Array.from(map)); // => [['a', 1], [42, 2], [true, 4]]
let map = new Map([['a', 1], ['b', 2], ['c', 3]]);
for (let [key, value] of map) {
console.log(key); // => 'a', 'b', 'c'
console.log(value); // => 1, 2, 3
}
for (let value of map.values()) console.log(value); // => 1, 2, 3
for (let key of map.keys()) console.log(key); // => 'a', 'b', 'c'
for (let [key, value] of map.entries()) {
console.log(key); // => 'a', 'b', 'c'
console.log(value); // => 1, 2, 3
}
const map = Map.groupBy([1, 2, 3, 4, 5], it => it % 2);
map.get(1); // => [1, 3, 5]
map.get(0); // => [2, 4]Set⬆
Modules es.set, es.set.difference.v2, es.set.intersection.v2, es.set.is-disjoint-from.v2, es.set.is-subset-of.v2, es.set.is-superset-of.v2, es.set.symmetric-difference.v2, es.set.union.v2
class Set {
constructor(iterable?: Iterable<value>): Set;
add(key: any): this;
clear(): void;
delete(key: any): boolean;
forEach((value: any, key: any, target: any) => void, thisArg: any): void;
has(key: any): boolean;
values(): Iterator<value>;
keys(): Iterator<value>;
entries(): Iterator<[value, value]>;
difference(other: SetLike<mixed>): Set;
intersection(other: SetLike<mixed>): Set;
isDisjointFrom(other: SetLike<mixed>): boolean;
isSubsetOf(other: SetLike<mixed>): boolean;
isSupersetOf(other: SetLike<mixed>): boolean;
symmetricDifference(other: SetLike<mixed>): Set;
union(other: SetLike<mixed>): Set;
@@iterator(): Iterator<value>;
readonly attribute size: number;
}core-js(-pure)/es|stable|actual|full/set
core-js(-pure)/es|stable|actual|full/set/difference
core-js(-pure)/es|stable|actual|full/set/intersection
core-js(-pure)/es|stable|actual|full/set/is-disjoint-from
core-js(-pure)/es|stable|actual|full/set/is-subset-of
core-js(-pure)/es|stable|actual|full/set/is-superset-of
core-js(-pure)/es|stable|actual|full/set/symmetric-difference
core-js(-pure)/es|stable|actual|full/set/union
let 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(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']
let set = new Set([1, 2, 3, 2, 1]);
for (let value of set) console.log(value); // => 1, 2, 3
for (let value of set.values()) console.log(value); // => 1, 2, 3
for (let key of set.keys()) console.log(key); // => 1, 2, 3
for (let [key, value] of set.entries()) {
console.log(key); // => 1, 2, 3
console.log(value); // => 1, 2, 3
}
new Set([1, 2, 3]).union(new Set([3, 4, 5])); // => Set {1, 2, 3, 4, 5}
new Set([1, 2, 3]).intersection(new Set([3, 4, 5])); // => Set {3}
new Set([1, 2, 3]).difference(new Set([3, 4, 5])); // => Set {1, 2}
new Set([1, 2, 3]).symmetricDifference(new Set([3, 4, 5])); // => Set {1, 2, 4, 5}
new Set([1, 2, 3]).isDisjointFrom(new Set([4, 5, 6])); // => true
new Set([1, 2, 3]).isSubsetOf(new Set([5, 4, 3, 2, 1])); // => true
new Set([5, 4, 3, 2, 1]).isSupersetOf(new Set([1, 2, 3])); // => trueWeakMap⬆
Module es.weak-map.
class WeakMap {
constructor(iterable?: Iterable<[key, value]>): WeakMap;
delete(key: Object): boolean;
get(key: Object): any;
has(key: Object): boolean;
set(key: Object, val: any): this;
}core-js(-pure)/es|stable|actual|full/weak-map
let a = [1];
let b = [2];
let c = [3];
let weakmap = new WeakMap([[a, 1], [b, 2]]);
weakmap.set(c, 3).set(b, 4);
console.log(weakmap.has(a)); // => true
console.log(weakmap.has([1])); // => false
console.log(weakmap.get(a)); // => 1
weakmap.delete(a);
console.log(weakmap.get(a)); // => undefined
// Private properties store:
let Person = (() => {
let names = new WeakMap;
return class {
constructor(name) {
names.set(this, name);
}
getName() {
return names.get(this);
}
}
})();
let person = new Person('Vasya');
console.log(person.getName()); // => 'Vasya'
for (let key in person) console.log(key); // => only 'getName'WeakSet⬆
Module es.weak-set.
class WeakSet {
constructor(iterable?: Iterable<value>): WeakSet;
add(key: Object): this;
delete(key: Object): boolean;
has(key: Object): boolean;
}core-js(-pure)/es|stable|actual|full/weak-set
let a = [1];
let b = [2];
let c = [3];
let weakset = new WeakSet([a, b, a]);
weakset.add(c).add(b).add(c);
console.log(weakset.has(b)); // => true
console.log(weakset.has([2])); // => false
weakset.delete(b);
console.log(weakset.has(b)); // => falseCaveats when using collections polyfill:⬆
- 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.
- Native symbols as
WeakMapkeys can't be properly polyfilled without memory leaks.
ECMAScript: Typed Arrays⬆
Implementations and fixes for 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 es.array-buffer.constructor, es.array-buffer.is-view, esnext.array-buffer.detached, es.array-buffer.slice, esnext.array-buffer.transfer, esnext.array-buffer.transfer-to-fixed-length es.data-view, es.typed-array.int8-array, es.typed-array.uint8-array, es.typed-array.uint8-clamped-array, es.typed-array.int16-array, es.typed-array.uint16-array, es.typed-array.int32-array, es.typed-array.uint32-array, es.typed-array.float32-array, es.typed-array.float64-array, es.typed-array.copy-within, es.typed-array.every, es.typed-array.fill, es.typed-array.filter, es.typed-array.find, es.typed-array.find-index, es.typed-array.find-last, es.typed-array.find-last-index, es.typed-array.for-each, es.typed-array.from, es.typed-array.includes, es.typed-array.index-of, es.typed-array.iterator, es.typed-array.last-index-of, es.typed-array.map, es.typed-array.of, es.typed-array.reduce, es.typed-array.reduce-right, es.typed-array.reverse, es.typed-array.set, es.typed-array.slice, es.typed-array.some, es.typed-array.sort, es.typed-array.subarray, es.typed-array.to-locale-string, es.typed-array.to-string, es.typed-array.at, es.typed-array.to-reversed, es.typed-array.to-sorted, es.typed-array.with.
class ArrayBuffer {
constructor(length: any): ArrayBuffer;
readonly attribute byteLength: number;
readonly attribute detached: boolean;
slice(start: any, end: any): ArrayBuffer;
transfer(newLength?: number): ArrayBuffer;
transferToFixedLength(newLength?: number): ArrayBuffer;
static isView(arg: any): boolean;
}
class DataView {
constructor(buffer: ArrayBuffer, byteOffset?: number, byteLength?: number): DataView;
getInt8(offset: any): int8;
getUint8(offset: any): uint8
getInt16(offset: any, littleEndian?: boolean = false): int16;
getUint16(offset: any, littleEndian?: boolean = false): uint16;
getInt32(offset: any, littleEndian?: boolean = false): int32;
getUint32(offset: any, littleEndian?: boolean = false): uint32;
getFloat32(offset: any, littleEndian?: boolean = false): float32;
getFloat64(offset: any, littleEndian?: boolean = false): float64;
setInt8(offset: any, value: any): void;
setUint8(offset: any, value: any): void;
setInt16(offset: any, value: any, littleEndian?: boolean = false): void;
setUint16(offset: any, value: any, littleEndian?: boolean = false): void;
setInt32(offset: any, value: any, littleEndian?: boolean = false): void;
setUint32(offset: any, value: any, littleEndian?: boolean = false): void;
setFloat32(offset: any, value: any, littleEndian?: boolean = false): void;
setFloat64(offset: any, value: any, littleEndian?: boolean = false): void;
readonly attribute buffer: ArrayBuffer;
readonly attribute byteLength: number;
readonly attribute byteOffset: number;
}
class [
Int8Array,
Uint8Array,
Uint8ClampedArray,
Int16Array,
Uint16Array,
Int32Array,
Uint32Array,
Float32Array,
Float64Array,
] extends %TypedArray% {
constructor(length: number): %TypedArray%;
constructor(object: %TypedArray% | Iterable | ArrayLike): %TypedArray%;
constructor(buffer: ArrayBuffer, byteOffset?: number, length?: number): %TypedArray%
}
class %TypedArray% {
at(index: int): number;
copyWithin(target: number, start: number, end?: number): this;
entries(): Iterator<[index, value]>;
every(callbackfn: (value: number, index: number, target: %TypedArray%) => boolean, thisArg?: any): boolean;
fill(value: number, start?: number, end?: number): this;
filter(callbackfn: (value: number, index: number, target: %TypedArray%) => boolean, thisArg?: any): %TypedArray%;
find(callbackfn: (value: number, index: number, target: %TypedArray%) => boolean), thisArg?: any): any;
findIndex(callbackfn: (value: number, index: number, target: %TypedArray%) => boolean, thisArg?: any): uint;
findLast(callbackfn: (value: any, index: number, target: %TypedArray%) => boolean, thisArg?: any): any;
findLastIndex(callbackfn: (value: any, index: number, target: %TypedArray%) => boolean, thisArg?: any): uint;
forEach(callbackfn: (value: number, index: number, target: %TypedArray%) => void, thisArg?: any): void;
includes(searchElement: any, from?: number): boolean;
indexOf(searchElement: any, from?: number): number;
join(separator: string = ','): string;
keys(): Iterator<index>;
lastIndexOf(searchElement: any, from?: number): number;
map(mapFn: (value: number, index: number, target: %TypedArray%) => number, thisArg?: any): %TypedArray%;
reduce(callbackfn: (memo: any, value: number, index: number, target: %TypedArray%) => any, initialValue?: any): any;
reduceRight(callbackfn: (memo: any, value: number, index: number, target: %TypedArray%) => any, initialValue?: any): any;
reverse(): this;
set(array: ArrayLike, offset?: number): void;
slice(start?: number, end?: number): %TypedArray%;
some(callbackfn: (value: number, index: number, target: %TypedArray%) => boolean, thisArg?: any): boolean;
sort(comparefn?: (a: number, b: number) => number): this; // with modern behavior like stable sort
subarray(begin?: number, end?: number): %TypedArray%;
toReversed(): %TypedArray%;
toSorted(comparefn?: (a: any, b: any) => number): %TypedArray%;
toString(): string;
toLocaleString(): string;
values(): Iterator<value>;
with(index: includes, value: any): %TypedArray%;
@@iterator(): Iterator<value>;
readonly attribute buffer: ArrayBuffer;
readonly attribute byteLength: number;
readonly attribute byteOffset: number;
readonly attribute length: number;
BYTES_PER_ELEMENT: number;
static from(items: Iterable | ArrayLike, mapFn?: (value: any, index: number) => any, thisArg?: any): %TypedArray%;
static of(...args: Array<mixed>): %TypedArray%;
static BYTES_PER_ELEMENT: number;
}core-js/es|stable|actual|full/array-buffer
core-js/es|stable|actual|full/array-buffer/constructor
core-js/es|stable|actual|full/array-buffer/is-view
core-js/es|stable|actual|full/array-buffer/detached
core-js/es|stable|actual|full/array-buffer/slice
core-js/es|stable|actual|full/array-buffer/transfer
core-js/es|stable|actual|full/array-buffer/transfer-to-fixed-length
core-js/es|stable|actual|full/data-view
core-js/es|stable|actual|full/typed-array
core-js/es|stable|actual|full/typed-array/int8-array
core-js/es|stable|actual|full/typed-array/uint8-array
core-js/es|stable|actual|full/typed-array/uint8-clamped-array
core-js/es|stable|actual|full/typed-array/int16-array
core-js/es|stable|actual|full/typed-array/uint16-array
core-js/es|stable|actual|full/typed-array/int32-array
core-js/es|stable|actual|full/typed-array/uint32-array
core-js/es|stable|actual|full/typed-array/float32-array
core-js/es|stable|actual|full/typed-array/float64-array
core-js/es|stable|actual|full/typed-array/at
core-js/es|stable|actual|full/typed-array/copy-within
core-js/es|stable|actual|full/typed-array/entries
core-js/es|stable|actual|full/typed-array/every
core-js/es|stable|actual|full/typed-array/fill
core-js/es|stable|actual|full/typed-array/filter
core-js/es|stable|actual|full/typed-array/find
core-js/es|stable|actual|full/typed-array/find-index
core-js/es|stable|actual|full/typed-array/find-last
core-js/es|stable|actual|full/typed-array/find-last-index
core-js/es|stable|actual|full/typed-array/for-each
core-js/es|stable|actual|full/typed-array/from
core-js/es|stable|actual|full/typed-array/includes
core-js/es|stable|actual|full/typed-array/index-of
core-js/es|stable|actual|full/typed-array/iterator
core-js/es|stable|actual|full/typed-array/join
core-js/es|stable|actual|full/typed-array/keys
core-js/es|stable|actual|full/typed-array/last-index-of
core-js/es|stable|actual|full/typed-array/map
core-js/es|stable|actual|full/typed-array/of
core-js/es|stable|actual|full/typed-array/reduce
core-js/es|stable|actual|full/typed-array/reduce-right
core-js/es|stable|actual|full/typed-array/reverse
core-js/es|stable|actual|full/typed-array/set
core-js/es|stable|actual|full/typed-array/slice
core-js/es|stable|actual|full/typed-array/some
core-js/es|stable|actual|full/typed-array/sort
core-js/es|stable|actual|full/typed-array/subarray
core-js/es|stable|actual|full/typed-array/to-locale-string
core-js/es|stable|actual|full/typed-array/to-reversed
core-js/es|stable|actual|full/typed-array/to-sorted
core-js/es|stable|actual|full/typed-array/to-string
core-js/es|stable|actual|full/typed-array/values
core-js/es|stable|actual|full/typed-array/with
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]
let buffer = new ArrayBuffer(8);
let 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]
let typed = new Uint8Array([1, 2, 3]);
let a = typed.slice(1); // => [2, 3]
typed.buffer === a.buffer; // => false
let 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 (let value of typed) console.log(value); // => 1, 2, 3
for (let value of typed.values()) console.log(value); // => 1, 2, 3
for (let key of typed.keys()) console.log(key); // => 0, 1, 2
for (let [key, value] of typed.entries()) {
console.log(key); // => 0, 1, 2
console.log(value); // => 1, 2, 3
}
new Int32Array([1, 2, 3]).at(1); // => 2
new Int32Array([1, 2, 3]).at(-1); // => 3
buffer = Int8Array.of(1, 2, 3, 4, 5, 6, 7, 8).buffer;
console.log(buffer.byteLength); // => 8
console.log(buffer.detached); // => false
const newBuffer = buffer.transfer(4);
console.log(buffer.byteLength); // => 0
console.log(buffer.detached); // => true
console.log(newBuffer.byteLength); // => 4
console.log(newBuffer.detached); // => false
console.log([...new Int8Array(newBuffer)]); // => [1, 2, 3, 4]Caveats when using typed arrays polyfills:⬆
- Polyfills of Typed Arrays constructors work completely how should work by the spec, but because of internal usage of getters / setters on each instance, are slow and consumes significant memory. However, polyfills of Typed Arrays constructors required mainly for old IE, all modern engines have native Typed Arrays constructors and require only fixes of constructors and polyfills of methods.
ArrayBuffer.prototype.{ transfer, transferToFixedLength }polyfilled only in runtime with nativestructuredClonewithArrayBuffertransfer orMessageChannelsupport.
ECMAScript: Reflect⬆
Modules es.reflect.apply, es.reflect.construct, es.reflect.define-property, es.reflect.delete-property, es.reflect.get, es.reflect.get-own-property-descriptor, es.reflect.get-prototype-of, es.reflect.has, es.reflect.is-extensible, es.reflect.own-keys, es.reflect.prevent-extensions, es.reflect.set, es.reflect.set-prototype-of.
namespace Reflect {
apply(target: Function, thisArgument: any, argumentsList: Array<mixed>): any;
construct(target: Function, argumentsList: Array<mixed>, newTarget?: Function): Object;
defineProperty(target: Object, propertyKey: PropertyKey, attributes: PropertyDescriptor): boolean;
deleteProperty(target: Object, propertyKey: PropertyKey): boolean;
get(target: Object, propertyKey: PropertyKey, receiver?: any): any;
getOwnPropertyDescriptor(target: Object, propertyKey: PropertyKey): PropertyDescriptor | void;
getPrototypeOf(target: Object): Object | null;
has(target: Object, propertyKey: PropertyKey): boolean;
isExtensible(target: Object): boolean;
ownKeys(target: Object): Array<string | symbol>;
preventExtensions(target: Object): boolean;
set(target: Object, propertyKey: PropertyKey, V: any, receiver?: any): boolean;
setPrototypeOf(target: Object, proto: Object | null): boolean; // required __proto__ - IE11+
}core-js(-pure)/es|stable|actual|full/reflect
core-js(-pure)/es|stable|actual|full/reflect/apply
core-js(-pure)/es|stable|actual|full/reflect/construct
core-js(-pure)/es|stable|actual|full/reflect/define-property
core-js(-pure)/es|stable|actual|full/reflect/delete-property
core-js(-pure)/es|stable|actual|full/reflect/get
core-js(-pure)/es|stable|actual|full/reflect/get-own-property-descriptor
core-js(-pure)/es|stable|actual|full/reflect/get-prototype-of
core-js(-pure)/es|stable|actual|full/reflect/has
core-js(-pure)/es|stable|actual|full/reflect/is-extensible
core-js(-pure)/es|stable|actual|full/reflect/own-keys
core-js(-pure)/es|stable|actual|full/reflect/prevent-extensions
core-js(-pure)/es|stable|actual|full/reflect/set
core-js(-pure)/es|stable|actual|full/reflect/set-prototype-of
let object = { a: 1 };
Object.defineProperty(object, 'b', { value: 2 });
object[Symbol('c')] = 3;
Reflect.ownKeys(object); // => ['a', 'b', Symbol(c)]
function C(a, b) {
this.c = a + b;
}
let instance = Reflect.construct(C, [20, 22]);
instance.c; // => 42ECMAScript: JSON⬆
Since JSON object is missed only in very old engines like IE7-, core-js does not provide a full JSON polyfill, however, fix already existing implementations by the current standard, for example, well-formed JSON.stringify. JSON also fixed in other modules - for example, Symbol polyfill fixes JSON.stringify for correct work with symbols.
Module es.json.to-string-tag and es.json.stringify.
namespace JSON {
stringify(value: any, replacer?: Array<string | number> | (this: any, key: string, value: any) => any, space?: string | number): string | void;
@@toStringTag: 'JSON';
}core-js(-pure)/es|stable|actual|full/json/stringify
core-js(-pure)/es|stable|actual|full/json/to-string-tagJSON.stringify({ '𠮷': ['\uDF06\uD834'] }); // => '{"𠮷":["\\udf06\\ud834"]}'ECMAScript: globalThis⬆
Module es.global-this.
let globalThis: GlobalThisValue;core-js(-pure)/es|stable|actual|full/global-thisglobalThis.Array === Array; // => trueECMAScript proposals⬆
Finished proposals⬆
Finished (stage 4) proposals already marked in core-js as stable ECMAScript, they are available in core-js/stable and core-js/es namespace, you can find then in related sections of this doc. However, even for finished proposals, core-js provide a way to include only features for a specific proposal like core-js/proposals/proposal-name.
let globalThis: Object;core-js/proposals/global-thisclass Array {
at(index: int): any;
}
class String {
at(index: int): string;
}
class %TypedArray% {
at(index: int): number;
}core-js/proposals/relative-indexing-method
class Array {
includes(searchElement: any, from?: number): boolean;
}
class %TypedArray% {
includes(searchElement: any, from?: number): boolean;
}core-js/proposals/array-includes
class Array {
flat(depthArg?: number = 1): Array<mixed>;
flatMap(mapFn: (value: any, index: number, target: any) => any, thisArg: any): Array<mixed>;
}core-js/proposals/array-flat-map
class Array {
findLast(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): any;
findLastIndex(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): uint;
}
class %TypedArray% {
findLast(callbackfn: (value: any, index: number, target: %TypedArray%) => boolean, thisArg?: any): any;
findLastIndex(callbackfn: (value: any, index: number, target: %TypedArray%) => boolean, thisArg?: any): uint;
}core-js/proposals/array-find-from-last
class Array {
toReversed(): Array<mixed>;
toSpliced(start?: number, deleteCount?: number, ...items: Array<mixed>): Array<mixed>;
toSorted(comparefn?: (a: any, b: any) => number): Array<mixed>;
with(index: includes, value: any): Array<mixed>;
}
class %TypedArray% {
toReversed(): %TypedArray%;
toSorted(comparefn?: (a: any, b: any) => number): %TypedArray%;
with(index: includes, value: any): %TypedArray%;
}core-js/proposals/change-array-by-copy-stage-4
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-reversed
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-sorted
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-spliced
core-js(-pure)/es|stable|actual|full/array(/virtual)/with
core-js/es|stable|actual|full/typed-array/to-reversed
core-js/es|stable|actual|full/typed-array/to-sorted
core-js/es|stable|actual|full/typed-array/with
class Object {
static groupBy(items: Iterable, callbackfn: (value: any, index: number) => key): { [key]: Array<mixed> };
}
class Map {
static groupBy(items: Iterable, callbackfn: (value: any, index: number) => key): Map<key, Array<mixed>>;
}core-js/proposals/array-grouping-v2
class ArrayBuffer {
readonly attribute detached: boolean;
transfer(newLength?: number): ArrayBuffer;
transferToFixedLength(newLength?: number): ArrayBuffer;
}core-js/proposals/array-buffer-transferclass Object {
static entries(object: Object): Array<[string, mixed]>;
static values(object: any): Array<mixed>;
}core-js/proposals/object-values-entries
class Object {
static fromEntries(iterable: Iterable<[key, value]>): Object;
}core-js/proposals/object-from-entries
class Object {
static getOwnPropertyDescriptors(object: any): { [property: PropertyKey]: PropertyDescriptor };
}core-js/proposals/object-getownpropertydescriptors
class Object {
static hasOwn(object: object, key: PropertyKey): boolean;
}core-js/proposals/accessible-object-hasownproperty
class String {
padStart(length: number, fillStr?: string = ' '): string;
padEnd(length: number, fillStr?: string = ' '): string;
}core-js/proposals/string-padding
class String {
matchAll(regexp: RegExp): Iterator;
}core-js/proposals/string-match-allclass String {
replaceAll(searchValue: string | RegExp, replaceString: string | (searchValue, index, this) => string): string;
}core-js/proposals/string-replace-all-stage-4class String {
trimLeft(): string;
trimRight(): string;
trimStart(): string;
trimEnd(): string;
}core-js/proposals/string-left-right-trim// patched for support `RegExp` dotAll (`s`) flag:
class RegExp {
constructor(pattern: RegExp | string, flags?: string): RegExp;
exec(): Array<string | undefined> | null;
readonly attribute dotAll: boolean;
readonly attribute flags: string;
}core-js/proposals/regexp-dotall-flag// patched for support `RegExp` named capture groups:
class RegExp {
constructor(pattern: RegExp | string, flags?: string): RegExp;
exec(): Array<string | undefined> | null;
@@replace(string: string, replaceValue: Function | string): string;
}core-js/proposals/regexp-named-groupsclass Promise {
static allSettled(iterable: Iterable): Promise;
}core-js/proposals/promise-all-settledclass AggregateError {
constructor(errors: Iterable, message: string): AggregateError;
errors: Array<any>;
message: string;
}
class Promise {
static any(promises: Iterable): Promise<any>;
}core-js/proposals/promise-anyclass Promise {
finally(onFinally: Function): Promise;
}core-js/proposals/promise-finallyclass Promise {
static withResolvers(): { promise: Promise, resolve: function, reject: function };
}core-js/proposals/promise-with-resolversclass Symbol {
static asyncIterator: @@asyncIterator;
}core-js/proposals/async-iterationclass Symbol {
readonly attribute description: string | void;
}core-js/proposals/symbol-descriptionnamespace JSON {
stringify(target: any, replacer?: Function | Array, space?: string | number): string | void;
}core-js/proposals/well-formed-stringifyclass String {
isWellFormed(): boolean;
toWellFormed(): string;
}core-js/proposals/well-formed-unicode-stringsclass Set {
difference(other: SetLike<mixed>): Set;
intersection(other: SetLike<mixed>): Set;
isDisjointFrom(other: SetLike<mixed>): boolean;
isSubsetOf(other: SetLike<mixed>): boolean;
isSupersetOf(other: SetLike<mixed>): boolean;
symmetricDifference(other: SetLike<mixed>): Set;
union(other: SetLike<mixed>): Set;
}core-js/proposals/set-methods-v2Stage 3 proposals⬆
core-js/stage/3 entry point contains only stage 3 proposals, core-js/stage/2.7 - stage 2.7 and stage 3, etc.
core-js(-pure)/stage/3Modules esnext.iterator.constructor, esnext.iterator.drop, esnext.iterator.every, esnext.iterator.filter, esnext.iterator.find, esnext.iterator.flat-map, esnext.iterator.for-each, esnext.iterator.from, esnext.iterator.map, esnext.iterator.reduce, esnext.iterator.some, esnext.iterator.take, esnext.iterator.to-array
class Iterator {
static from(iterable: Iterable<any> | Iterator<any>): Iterator<any>;
drop(limit: uint): Iterator<any>;
every(callbackfn: (value: any, counter: uint) => boolean): boolean;
filter(callbackfn: (value: any, counter: uint) => boolean): Iterator<any>;
find(callbackfn: (value: any, counter: uint) => boolean)): any;
flatMap(callbackfn: (value: any, counter: uint) => Iterable<any> | Iterator<any>): Iterator<any>;
forEach(callbackfn: (value: any, counter: uint) => void): void;
map(callbackfn: (value: any, counter: uint) => any): Iterator<any>;
reduce(callbackfn: (memo: any, value: any, counter: uint) => any, initialValue: any): any;
some(callbackfn: (value: any, counter: uint) => boolean): boolean;
take(limit: uint): Iterator<any>;
toArray(): Array<any>;
@@toStringTag: 'Iterator'
}core-js/proposals/iterator-helpers-stage-3-2
core-js(-pure)/actual|full/iterator
core-js(-pure)/actual|full/iterator/drop
core-js(-pure)/actual|full/iterator/every
core-js(-pure)/actual|full/iterator/filter
core-js(-pure)/actual|full/iterator/find
core-js(-pure)/actual|full/iterator/flat-map
core-js(-pure)/actual|full/iterator/for-each
core-js(-pure)/actual|full/iterator/from
core-js(-pure)/actual|full/iterator/map
core-js(-pure)/actual|full/iterator/reduce
core-js(-pure)/actual|full/iterator/some
core-js(-pure)/actual|full/iterator/take
core-js(-pure)/actual|full/iterator/to-array[1, 2, 3, 4, 5, 6, 7].values()
.drop(1)
.take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
Iterator.from({
next: () => ({ done: Math.random() > .9, value: Math.random() * 10 | 0 })
}).toArray(); // => [7, 6, 3, 0, 2, 8]Caveats:⬆
- For preventing prototypes pollution, in the
pureversion, new%IteratorPrototype%methods are not added to the real%IteratorPrototype%, they available only on wrappers - instead of[].values().map(fn)useIterator.from([]).map(fn).
Modules esnext.array.from-async.
class Array {
static fromAsync(asyncItems: AsyncIterable | Iterable | ArrayLike, mapfn?: (value: any, index: number) => any, thisArg?: any): Array;
}core-js/proposals/array-from-async-stage-2
core-js(-pure)/actual|full/array/from-asyncawait Array.fromAsync((async function * (){ yield * [1, 2, 3] })(), i => i * i); // => [1, 4, 9]Modules esnext.json.is-raw-json, esnext.json.parse, esnext.json.raw-json.
namespace JSON {
isRawJSON(O: any): boolean;
// patched for source support
parse(text: string, reviver?: (this: any, key: string, value: any, context: { source?: string }) => any): any;
rawJSON(text: any): RawJSON;
// patched for `JSON.rawJSON` support
stringify(value: any, replacer?: Array<string | number> | (this: any, key: string, value: any) => any, space?: string | number): string | void;
}core-js/proposals/json-parse-with-source
core-js(-pure)/actual|full/json/is-raw-json
core-js(-pure)/actual|full/json/parse
core-js(-pure)/actual|full/json/raw-json
core-js(-pure)/actual|full/json/stringifyfunction digitsToBigInt(key, val, { source }) {
return /^[0-9]+$/.test(source) ? BigInt(source) : val;
}
function bigIntToRawJSON(key, val) {
return typeof val === "bigint" ? JSON.rawJSON(String(val)) : val;
}
const tooBigForNumber = BigInt(Number.MAX_SAFE_INTEGER) + 2n;
JSON.parse(String(tooBigForNumber), digitsToBigInt) === tooBigForNumber; // true
const wayTooBig = BigInt("1" + "0".repeat(1000));
JSON.parse(String(wayTooBig), digitsToBigInt) === wayTooBig; // true
const embedded = JSON.stringify({ tooBigForNumber }, bigIntToRawJSON);
embedded === '{"tooBigForNumber":9007199254740993}'; // trueModules esnext.data-view.get-float16, esnext.data-view.set-float16 and esnext.math.f16round
class DataView {
getFloat16(offset: any): number
setFloat16(offset: any, value: any): void;
}
namespace Math {
fround(number: any): number;
}core-js/proposals/float16
core-js/actual|full/dataview/get-float16
core-js/actual|full/dataview/set-float16
core-js/actual|full/math/f16roundconsole.log(Math.f16round(1.337)); // => 1.3369140625
const view = new DataView(new ArrayBuffer(2));
view.setFloat16(0, 1.337);
console.log(view.getFloat16(0)); // => 1.3369140625Modules esnext.uint8-array.from-base64, esnext.uint8-array.from-hex, esnext.uint8-array.to-base64, esnext.uint8-array.to-hex.
class Uint8Array {
static fromBase64(string, options?: { alphabet?: 'base64' | 'base64url', strict?: boolean }): Uint8Array;
static fromHex(string): Uint8Array;
toBase64(options?: { alphabet?: 'base64' | 'base64url' }): string;
toHex(): string;
}[*CommonJS entry points:*](#commonjs-api)
```js
core-js/proposals/array-buffer-base64
core-js(-pure)/full/typed-array/from-base64
core-js(-pure)/full/typed-array/from-hex
core-js(-pure)/full/typed-array/to-base64
core-js(-pure)/full/typed-array/to-hex
Example:
let arr = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);
console.log(arr.toBase64()); // => 'SGVsbG8gV29ybGQ='
console.log(arr.toHex()); // => '48656c6c6f20576f726c64'
console.log(Uint8Array.fromBase64('SGVsbG8gV29ybGQ=')); // => Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100])
console.log(Uint8Array.fromHex('48656c6c6f20576f726c64')); // => Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100])Note: This is only built-ins for this proposal, using syntax support requires transpiler support.
Modules esnext.symbol.dispose, esnext.disposable-stack.constructor, esnext.suppressed-error.constructor, esnext.iterator.dispose, esnext.symbol.async-dispose, esnext.async-disposable-stack.constructor, esnext.async-iterator.async-dispose.
class Symbol {
static asyncDispose: @@asyncDispose;
static dispose: @@dispose;
}
class DisposableStack {
constructor(): DisposableStack;
dispose(): undefined;
use(value: Disposable): value;
adopt(value: object, onDispose: Function): value;
defer(onDispose: Function): undefined;
@@dispose(): undefined;
@@toStringTag: 'DisposableStack';
}
class AsyncDisposableStack {
constructor(): AsyncDisposableStack;
disposeAsync(): Promise<undefined>;
use(value: AsyncDisposable | Disposable): value;
adopt(value: object, onDispose: Function): value;
defer(onDispose: Function): undefined;
@@asyncDispose(): Promise<undefined>;
@@toStringTag: 'AsyncDisposableStack';
}
class SuppressedError extends Error {
constructor(error: any, suppressed: any, message?: string): SuppressedError;
error: any;
suppressed: any;
message: string;
cause: any;
}
class Iterator {
@@dispose(): undefined;
}
class AsyncIterator {
@@asyncDispose(): Promise<undefined>;
}core-js/proposals/explicit-resource-management
core-js(-pure)/actual|full/symbol/async-dispose
core-js(-pure)/actual|full/symbol/dispose
core-js(-pure)/actual|full/disposable-stack
core-js(-pure)/actual|full/async-disposable-stack
core-js(-pure)/actual|full/suppressed-error
core-js(-pure)/actual|full/iterator/dispose
core-js(-pure)/actual|full/async-iterator/async-disposeModules esnext.symbol.metadata and esnext.function.metadata.
class Symbol {
static metadata: @@metadata;
}
class Function {
@@metadata: null;
}core-js/proposals/decorator-metadata-v2
core-js(-pure)/actual|full/symbol/metadata
core-js(-pure)/actual|full/function/metadata
Stage 2.7 proposals⬆
core-js(-pure)/stage/2.7
Module esnext.promise.try
class Promise {
static try(callbackfn: Function): Promise;
}core-js/proposals/promise-try
core-js(-pure)/full/promise/tryPromise.try(() => 42).then(it => console.log(`Promise, resolved as ${it}`));
Promise.try(() => { throw 42; }).catch(it => console.log(`Promise, rejected as ${it}`));
Promise.try(async () => 42).then(it => console.log(`Promise, resolved as ${it}`));
Promise.try(async () => { throw 42; }).catch(it => console.log(`Promise, rejected as ${it}`));Module esnext.math.sum-precise
class Math {
static sumPrecise(items: Iterable<number>): Number;
}core-js/proposals/math-sum
core-js(-pure)/full/math/sum-precise1e20 + 0.1 + -1e20; // => 0
Math.sumPrecise([1e20, 0.1, -1e20]); // => 0.1Stage 2 proposals⬆
core-js(-pure)/stage/2
Modules esnext.async-iterator.constructor, esnext.async-iterator.drop, esnext.async-iterator.every, esnext.async-iterator.filter, esnext.async-iterator.find, esnext.async-iterator.flat-map, esnext.async-iterator.for-each, esnext.async-iterator.from, esnext.async-iterator.map, esnext.async-iterator.reduce, esnext.async-iterator.some, esnext.async-iterator.take, esnext.async-iterator.to-array, , esnext.iterator.to-async
class Iterator {
toAsync(): AsyncIterator<any>;
}
class AsyncIterator {
static from(iterable: AsyncIterable<any> | Iterable<any> | AsyncIterator<any>): AsyncIterator<any>;
drop(limit: uint): AsyncIterator<any>;
every(async callbackfn: (value: any, counter: uint) => boolean): Promise<boolean>;
filter(async callbackfn: (value: any, counter: uint) => boolean): AsyncIterator<any>;
find(async callbackfn: (value: any, counter: uint) => boolean)): Promise<any>;
flatMap(async callbackfn: (value: any, counter: uint) => AsyncIterable<any> | Iterable<any> | AsyncIterator<any>): AsyncIterator<any>;
forEach(async callbackfn: (value: any, counter: uint) => void): Promise<void>;
map(async callbackfn: (value: any, counter: uint) => any): AsyncIterator<any>;
reduce(async callbackfn: (memo: any, value: any, counter: uint) => any, initialValue: any): Promise<any>;
some(async callbackfn: (value: any, counter: uint) => boolean): Promise<boolean>;
take(limit: uint): AsyncIterator<any>;
toArray(): Promise<Array>;
@@toStringTag: 'AsyncIterator'
}core-js/proposals/async-iterator-helpers
core-js(-pure)/actual|full/async-iterator
core-js(-pure)/actual|full/async-iterator/drop
core-js(-pure)/actual|full/async-iterator/every
core-js(-pure)/actual|full/async-iterator/filter
core-js(-pure)/actual|full/async-iterator/find
core-js(-pure)/actual|full/async-iterator/flat-map
core-js(-pure)/actual|full/async-iterator/for-each
core-js(-pure)/actual|full/async-iterator/from
core-js(-pure)/actual|full/async-iterator/map
core-js(-pure)/actual|full/async-iterator/reduce
core-js(-pure)/actual|full/async-iterator/some
core-js(-pure)/actual|full/async-iterator/take
core-js(-pure)/actual|full/async-iterator/to-array
core-js(-pure)/actual|full/iterator/to-asyncawait AsyncIterator.from([1, 2, 3, 4, 5, 6, 7])
.drop(1)
.take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
await [1, 2, 3].values().toAsync().map(async it => it ** 2).toArray(); // => [1, 4, 9]Caveats:⬆
- For preventing prototypes pollution, in the
pureversion, new%AsyncIteratorPrototype%methods are not added to the real%AsyncIteratorPrototype%, they available only on wrappers - instead of[].values().toAsync().map(fn)useAsyncIterator.from([]).map(fn). - Now, we have access to the real
%AsyncIteratorPrototype%only with usage async generators syntax. So, for compatibility the library with old browsers, we should useFunctionconstructor. However, that breaks compatibility with CSP. So, if you wanna use the real%AsyncIteratorPrototype%, you should setUSE_FUNCTION_CONSTRUCTORoption in thecore-js/configuratortotrue:
const configurator = require('core-js/configurator');
configurator({ USE_FUNCTION_CONSTRUCTOR: true });
require('core-js/actual/async-iterator');
(async function * () { /* empty */ })() instanceof AsyncIterator; // => true- As an alternative, you could pass to the
core-js/configuratoran object that will be considered as%AsyncIteratorPrototype%:
const configurator = require('core-js/configurator');
const { getPrototypeOf } = Object;
configurator({ AsyncIteratorPrototype: getPrototypeOf(getPrototypeOf(getPrototypeOf(async function * () { /* empty */ }()))) });
require('core-js/actual/async-iterator');
(async function * () { /* empty */ })() instanceof AsyncIterator; // => trueModule esnext.iterator.range
class Iterator {
range(start: number, end: number, options: { step: number = 1, inclusive: boolean = false } | step: number = 1): NumericRangeIterator;
range(start: bigint, end: bigint | Infinity | -Infinity, options: { step: bigint = 1n, inclusive: boolean = false } | step: bigint = 1n): NumericRangeIterator;
}core-js/proposals/number-range
core-js(-pure)/full/iterator/rangefor (const i of Iterator.range(1, 10)) {
console.log(i); // => 1, 2, 3, 4, 5, 6, 7, 8, 9
}
for (const i of Iterator.range(1, 10, { step: 3, inclusive: true })) {
console.log(i); // => 1, 4, 7, 10
}Modules esnext.map.emplace and esnext.weak-map.emplace
class Map {
emplace(key: any, { update: (value: any, key: any, handler: object) => updated: any, insert: (key: any, handler: object) => value: any): updated | value;
}
class WeakMap {
emplace(key: any, { update: (value: any, key: any, handler: object) => updated: any, insert: (key: any, handler: object) => value: any): updated | value;
}core-js/proposals/map-upsert-stage-2
core-js(-pure)/full/map/emplace
core-js(-pure)/full/weak-map/emplaceconst map = new Map([['a', 2]]);
map.emplace('a', { update: it => it ** 2, insert: () => 3}); // => 4
map.emplace('b', { update: it => it ** 2, insert: () => 3}); // => 3
console.log(map); // => Map { 'a': 4, 'b': 3 }Module esnext.array.is-template-object
class Array {
static isTemplateObject(value: any): boolean
}core-js/proposals/array-is-template-object
core-js(-pure)/full/array/is-template-objectExample:
console.log(Array.isTemplateObject((it => it)`qwe${ 123 }asd`)); // => trueModule esnext.string.dedent
class String {
static dedent(templateOrTag: { raw: Array<string> } | function, ...substitutions: Array<string>): string | function;
}core-js/proposals/string-dedent
core-js(-pure)/full/string/dedentconst message = 42;
console.log(String.dedent`
print('${ message }')
`); // => print('42')
String.dedent(console.log)`
print('${ message }')
`; // => ["print('", "')", raw: Array(2)], 42Module esnext.regexp.escape
class RegExp {
static escape(value: string): string
}core-js/proposals/regexp-escaping
core-js(-pure)/full/regexp/escapeconsole.log(RegExp.escape('10$')); // => '\\x310\\x24'
console.log(RegExp.escape('abcdefg_123456')); // => 'abcdefg_123456'
console.log(RegExp.escape('(){}[]|,.?*+-^$=<>\\/#&!%:;@~\'"`'));
// => '\\x28\\x29\\x7b\\x7d\\x5b\\x5d\\x7c\\x2c\\x2e\\x3f\\x2a\\x2b\\x2d\\x5e\\x24\\x3d\\x3c\\x3e\\x5c\\x2f\\x23\\x26\\x21\\x25\\x3a\\x3b\\x40\\x7e\\x27\\x22\\x60'
console.log(RegExp.escape('\u0009\u000A\u000B\u000C\u000D\u0020\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028\u2029\uFEFF'));
// => '\\x09\\x0a\\x0b\\x0c\\x0d\\x20\\xa0\\u1680\\u2000\\u2001\\u2002\\u2003\\u2004\\u2005\\u2006\\u2007\\u2008\\u2009\\u200a\\u202f\\u205f\\u3000\\u2028\\u2029\\ufeff'Modules esnext.symbol.is-registered-symbol, esnext.symbol.is-well-known-symbol.
class Symbol {
static isRegisteredSymbol(value: any): boolean;
static isWellKnownSymbol(value: any): boolean;
}[*CommonJS entry points:*](#commonjs-api)
```js
core-js/proposals/symbol-predicates-v2
core-js(-pure)/full/symbol/is-registered-symbol
core-js(-pure)/full/symbol/is-well-known-symbol
Symbol.isRegisteredSymbol(Symbol.for('key')); // => true
Symbol.isRegisteredSymbol(Symbol('key')); // => false
Symbol.isWellKnownSymbol(Symbol.iterator); // => true
Symbol.isWellKnownSymbol(Symbol('key')); // => falseStage 1 proposals⬆
core-js(-pure)/stage/1Modules esnext.observable and esnext.symbol.observable
class Observable {
constructor(subscriber: Function): Observable;
subscribe(observer: Function | { next?: Function, error?: Function, complete?: Function }): Subscription;
@@observable(): this;
static of(...items: Array<mixed>): Observable;
static from(x: Observable | Iterable): Observable;
static readonly attribute @@species: this;
}
class Symbol {
static observable: @@observable;
}core-js/proposals/observable
core-js(-pure)/full/observable
core-js(-pure)/full/symbol/observablenew Observable(observer => {
observer.next('hello');
observer.next('world');
observer.complete();
}).subscribe({
next(it) { console.log(it); },
complete() { console.log('!'); }
});Modules esnext.set.add-all, esnext.set.delete-all, esnext.set.every, esnext.set.filter, esnext.set.find, esnext.set.join, esnext.set.map, esnext.set.reduce, esnext.set.some, esnext.map.delete-all, esnext.map.every, esnext.map.filter, esnext.map.find, esnext.map.find-key, esnext.map.includes, esnext.map.key-by, esnext.map.key-of, esnext.map.map-keys, esnext.map.map-values, esnext.map.merge, esnext.map.reduce, esnext.map.some, esnext.map.update, esnext.weak-set.add-all, esnext.weak-set.delete-all, esnext.weak-map.delete-all
Modules esnext.set.of, esnext.set.from, esnext.map.of, esnext.map.from, esnext.weak-set.of, esnext.weak-set.from, esnext.weak-map.of, esnext.weak-map.from
class Set {
static of(...args: Array<mixed>): Set;
static from(iterable: Iterable<mixed>, mapFn?: (value: any, index: number) => any, thisArg?: any): Set;
addAll(...args: Array<mixed>): this;
deleteAll(...args: Array<mixed>): boolean;
every(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean;
filter(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): Set;
find(callbackfn: (value: any, key: any, target: any) => boolean), thisArg?: any): any;
join(separator: string = ','): string;
map(callbackfn: (value: any, key: any, target: any) => any, thisArg?: any): Set;
reduce(callbackfn: (memo: any, value: any, key: any, target: any) => any, initialValue?: any): any;
some(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean;
}
class Map {
static of(...args: Array<[key, value]>): Map;
static from(iterable: Iterable<mixed>, mapFn?: (value: any, index: number) => [key: any, value: any], thisArg?: any): Map;
static keyBy(iterable: Iterable<mixed>, callbackfn?: (value: any) => any): Map;
deleteAll(...args: Array<mixed>): boolean;
every(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean;
filter(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): Map;
find(callbackfn: (value: any, key: any, target: any) => boolean), thisArg?: any): any;
findKey(callbackfn: (value: any, key: any, target: any) => boolean), thisArg?: any): any;
includes(searchElement: any): boolean;
keyOf(searchElement: any): any;
mapKeys(mapFn: (value: any, index: number, target: any) => any, thisArg?: any): Map;
mapValues(mapFn: (value: any, index: number, target: any) => any, thisArg?: any): Map;
merge(...iterables: Array<Iterable>): this;
reduce(callbackfn: (memo: any, value: any, key: any, target: any) => any, initialValue?: any): any;
some(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean;
update(key: any, callbackfn: (value: any, key: any, target: any) => any, thunk?: (key: any, target: any) => any): this;
}
class WeakSet {
static of(...args: Array<mixed>): WeakSet;
static from(iterable: Iterable<mixed>, mapFn?: (value: any, index: number) => Object, thisArg?: any): WeakSet;
addAll(...args: Array<mixed>): this;
deleteAll(...args: Array<mixed>): boolean;
}
class WeakMap {
static of(...args: Array<[key, value]>): WeakMap;
static from(iterable: Iterable<mixed>, mapFn?: (value: any, index: number) => [key: Object, value: any], thisArg?: any): WeakMap;
deleteAll(...args: Array<mixed>): boolean;
}core-js/proposals/collection-methods
core-js/proposals/collection-of-from
core-js(-pure)/full/set/add-all
core-js(-pure)/full/set/delete-all
core-js(-pure)/full/set/every
core-js(-pure)/full/set/filter
core-js(-pure)/full/set/find
core-js(-pure)/full/set/from
core-js(-pure)/full/set/join
core-js(-pure)/full/set/map
core-js(-pure)/full/set/of
core-js(-pure)/full/set/reduce
core-js(-pure)/full/set/some
core-js(-pure)/full/map/delete-all
core-js(-pure)/full/map/every
core-js(-pure)/full/map/filter
core-js(-pure)/full/map/find
core-js(-pure)/full/map/find-key
core-js(-pure)/full/map/from
core-js(-pure)/full/map/includes
core-js(-pure)/full/map/key-by
core-js(-pure)/full/map/key-of
core-js(-pure)/full/map/map-keys
core-js(-pure)/full/map/map-values
core-js(-pure)/full/map/merge
core-js(-pure)/full/map/of
core-js(-pure)/full/map/reduce
core-js(-pure)/full/map/some
core-js(-pure)/full/map/update
core-js(-pure)/full/weak-set/add-all
core-js(-pure)/full/weak-set/delete-all
core-js(-pure)/full/weak-set/of
core-js(-pure)/full/weak-set/from
core-js(-pure)/full/weak-map/delete-all
core-js(-pure)/full/weak-map/of
core-js(-pure)/full/weak-map/from.of / .from examples:
Set.of(1, 2, 3, 2, 1); // => Set {1, 2, 3}
Map.from([[1, 2], [3, 4]], ([key, value]) => [key ** 2, value ** 2]); // => Map { 1: 4, 9: 16 }Modules esnext.composite-key and esnext.composite-symbol
function compositeKey(...args: Array<mixed>): object;
function compositeSymbol(...args: Array<mixed>): symbol;core-js/proposals/keys-composition
core-js(-pure)/full/composite-key
core-js(-pure)/full/composite-symbol// returns a symbol
const symbol = compositeSymbol({});
console.log(typeof symbol); // => 'symbol'
// works the same, but returns a plain frozen object without a prototype
const key = compositeKey({});
console.log(typeof key); // => 'object'
console.log({}.toString.call(key)); // => '[object Object]'
console.log(Object.getPrototypeOf(key)); // => null
console.log(Object.isFrozen(key)); // => true
const a = ['a'];
const b = ['b'];
const c = ['c'];
console.log(compositeSymbol(a) === compositeSymbol(a)); // => true
console.log(compositeSymbol(a) !== compositeSymbol(['a'])); // => true
console.log(compositeSymbol(a, 1) === compositeSymbol(a, 1)); // => true
console.log(compositeSymbol(a, b) !== compositeSymbol(b, a)); // => true
console.log(compositeSymbol(a, b, c) === compositeSymbol(a, b, c)); // => true
console.log(compositeSymbol(1, a) === compositeSymbol(1, a)); // => true
console.log(compositeSymbol(1, a, 2, b) === compositeSymbol(1, a, 2, b)); // => true
console.log(compositeSymbol(a, a) === compositeSymbol(a, a)); // => trueModules esnext.array.filter-reject and esnext.typed-array.filter-reject.
class Array {
filterReject(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): Array<mixed>;
}
class %TypedArray% {
filterReject(callbackfn: (value: number, index: number, target: %TypedArray%) => boolean, thisArg?: any): %TypedArray%;
}core-js/proposals/array-filtering-stage-1
core-js(-pure)/full/array(/virtual)/filter-reject
core-js/full/typed-array/filter-reject
[1, 2, 3, 4, 5].filterReject(it => it % 2); // => [2, 4]Modules esnext.array.unique-by and esnext.typed-array.unique-by
class Array {
uniqueBy(resolver?: (item: any) => any): Array<mixed>;
}
class %TypedArray% {
uniqueBy(resolver?: (item: any) => any): %TypedArray%;;
}core-js/proposals/array-unique
core-js(-pure)/full/array(/virtual)/unique-by
core-js/full/typed-array/unique-by
[1, 2, 3, 2, 1].uniqueBy(); // [1, 2, 3]
[
{ id: 1, uid: 10000 },
{ id: 2, uid: 10000 },
{ id: 3, uid: 10001 }
].uniqueBy(it => it.uid); // => [{ id: 1, uid: 10000 }, { id: 3, uid: 10001 }]Modules esnext.data-view.get-uint8-clamped and esnext.data-view.set-uint8-clamped
class DataView {
getUint8Clamped(offset: any): uint8
setUint8Clamped(offset: any, value: any): void;
}core-js/proposals/data-view-get-set-uint8-clamped
core-js/full/dataview/get-uint8-clamped
core-js/full/dataview/set-uint8-clampedconst view = new DataView(new ArrayBuffer(1));
view.setUint8Clamped(0, 100500);
console.log(view.getUint8Clamped(0)); // => 255Module esnext.number.from-string
class Number {
fromString(string: string, radix: number): number;
}core-js/proposals/number-from-string
core-js(-pure)/full/number/from-stringModule esnext.string.cooked
class String {
static cooked(template: Array<string>, ...substitutions: Array<string>): string;
}core-js/proposals/string-cooked
core-js(-pure)/full/string/cookedfunction safePath(strings, ...subs) {
return String.cooked(strings, ...subs.map(sub => encodeURIComponent(sub)));
}
let id = 'spottie?';
safePath`/cats/${ id }`; // => /cats/spottie%3FModule esnext.string.code-points
class String {
codePoints(): Iterator<{ codePoint, position }>;
}core-js/proposals/string-code-points
core-js(-pure)/full/string/code-pointsfor (let { codePoint, position } of 'qwe'.codePoints()) {
console.log(codePoint); // => 113, 119, 101
console.log(position); // => 0, 1, 2
}Module esnext.symbol.custom-matcher.
class Symbol {
static customMatcher: @@customMatcher;
}core-js/proposals/pattern-matching-v2
core-js(-pure)/full/symbol/custom-matcherModule esnext.symbol.custom-matcher.
class Symbol {
static customMatcher: @@customMatcher;
}core-js/proposals/pattern-extractors
core-js(-pure)/full/symbol/custom-matcherStage 0 proposals⬆
core-js(-pure)/stage/0Module esnext.function.demethodize
class Function {
demethodize(): Function;
}core-js/proposals/function-demethodize
core-js(-pure)/full/function/demethodize
core-js(-pure)/full/function/virtual/demethodize
const slice = Array.prototype.slice.demethodize();
slice([1, 2, 3], 1); // => [2, 3]Modules esnext.function.is-callable, esnext.function.is-constructor
class Function {
static isCallable(value: any): boolean;
static isConstructor(value: any): boolean;
}core-js/proposals/function-is-callable-is-constructor
core-js(-pure)/full/function/is-callable
core-js(-pure)/full/function/is-constructorFunction.isCallable(null); // => false
Function.isCallable({}); // => false
Function.isCallable(function () {}); // => true
Function.isCallable(() => {}); // => true
Function.isCallable(class {}); // => false
Function.isConstructor(null); // => false
Function.isConstructor({}); // => false
Function.isConstructor(function () {}); // => true
Function.isConstructor(() => {}); // => false
Function.isConstructor(class {}); // => truePre-stage 0 proposals⬆
core-js(-pure)/stage/preModules esnext.reflect.define-metadata, esnext.reflect.delete-metadata, esnext.reflect.get-metadata, esnext.reflect.get-metadata-keys, esnext.reflect.get-own-metadata, esnext.reflect.get-own-metadata-keys, esnext.reflect.has-metadata, esnext.reflect.has-own-metadata and esnext.reflect.metadata.
namespace Reflect {
defineMetadata(metadataKey: any, metadataValue: any, target: Object, propertyKey?: PropertyKey): void;
getMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): any;
getOwnMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): any;
hasMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): boolean;
hasOwnMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): boolean;
deleteMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): boolean;
getMetadataKeys(target: Object, propertyKey?: PropertyKey): Array<mixed>;
getOwnMetadataKeys(target: Object, propertyKey?: PropertyKey): Array<mixed>;
metadata(metadataKey: any, metadataValue: any): decorator(target: Object, targetKey?: PropertyKey) => void;
}core-js/proposals/reflect-metadata
core-js(-pure)/full/reflect/define-metadata
core-js(-pure)/full/reflect/delete-metadata
core-js(-pure)/full/reflect/get-metadata
core-js(-pure)/full/reflect/get-metadata-keys
core-js(-pure)/full/reflect/get-own-metadata
core-js(-pure)/full/reflect/get-own-metadata-keys
core-js(-pure)/full/reflect/has-metadata
core-js(-pure)/full/reflect/has-own-metadata
core-js(-pure)/full/reflect/metadatalet object = {};
Reflect.defineMetadata('foo', 'bar', object);
Reflect.ownKeys(object); // => []
Reflect.getOwnMetadataKeys(object); // => ['foo']
Reflect.getOwnMetadata('foo', object); // => 'bar'Web standards⬆
self⬆
getter self: GlobalThisValue;core-js(-pure)/stable|actual|full/selfself.Array === Array; // => truestructuredClone⬆
Spec, module web.structured-clone
function structuredClone(value: Serializable, { transfer?: Sequence<Transferable> }): any;core-js(-pure)/stable|actual|full/structured-cloneconst structured = [{ a: 42 }];
const sclone = structuredClone(structured);
console.log(sclone); // => [{ a: 42 }]
console.log(structured !== sclone); // => true
console.log(structured[0] !== sclone[0]); // => true
const circular = {};
circular.circular = circular;
const cclone = structuredClone(circular);
console.log(cclone.circular === cclone); // => true
structuredClone(42); // => 42
structuredClone({ x: 42 }); // => { x: 42 }
structuredClone([1, 2, 3]); // => [1, 2, 3]
structuredClone(new Set([1, 2, 3])); // => Set{ 1, 2, 3 }
structuredClone(new Map([['a', 1], ['b', 2]])); // => Map{ a: 1, b: 2 }
structuredClone(new Int8Array([1, 2, 3])); // => new Int8Array([1, 2, 3])
structuredClone(new AggregateError([1, 2, 3], 'message')); // => new AggregateError([1, 2, 3], 'message'))
structuredClone(new TypeError('message', { cause: 42 })); // => new TypeError('message', { cause: 42 })
structuredClone(new DOMException('message', 'DataCloneError')); // => new DOMException('message', 'DataCloneError')
structuredClone(document.getElementById('myfileinput')); // => new FileList
structuredClone(new DOMPoint(1, 2, 3, 4)); // => new DOMPoint(1, 2, 3, 4)
structuredClone(new Blob(['test'])); // => new Blob(['test'])
structuredClone(new ImageData(8, 8)); // => new ImageData(8, 8)
// etc.
structuredClone(new WeakMap()); // => DataCloneError on non-serializable typesCaveats when using structuredClone polyfill:⬆
- Many platform types cannot be transferred in most engines since we have no way to polyfill this behavior, however
.transferoption works for some platform types. I recommend avoiding this option. - Some specific platform types can't be cloned in old engines. Mainly it's very specific types or very old engines, but here are some exceptions. For example, we have no sync way to clone
ImageBitmapin Safari 14.0- or Firefox 83-, so it's recommended to look to the polyfill source if you wanna clone something specific.
Base64 utility methods⬆
Specification, MDN. Modules web.atob, web.btoa.
function atob(data: string): string;
function btoa(data: string): string;core-js(-pure)/stable|actual|full/atob
core-js(-pure)/stable|actual|full/btoabtoa('hi, core-js'); // => 'aGksIGNvcmUtanM='
atob('aGksIGNvcmUtanM='); // => 'hi, core-js'setTimeout and setInterval⬆
Module web.timers. Additional arguments fix for IE9-.
function setTimeout(callback: any, time: any, ...args: Array<mixed>): number;
function setInterval(callback: any, time: any, ...args: Array<mixed>): number;core-js(-pure)/stable|actual|full/set-timeout
core-js(-pure)/stable|actual|full/set-interval// Before:
setTimeout(log.bind(null, 42), 1000);
// After:
setTimeout(log, 1000, 42);setImmediate⬆
Module web.immediate. setImmediate polyfill.
function setImmediate(callback: any, ...args: Array<mixed>): number;
function clearImmediate(id: number): void;core-js(-pure)/stable|actual|full/set-immediate
core-js(-pure)/stable|actual|full/clear-immediatesetImmediate((arg1, arg2) => {
console.log(arg1, arg2); // => Message will be displayed with minimum delay
}, 'Message will be displayed', 'with minimum delay');
clearImmediate(setImmediate(() => {
console.log('Message will not be displayed');
}));queueMicrotask⬆
Spec, module web.queue-microtask
function queueMicrotask(fn: Function): void;core-js(-pure)/stable|actual|full/queue-microtaskqueueMicrotask(() => console.log('called as microtask'));URL and URLSearchParams⬆
URL standard implementation. Modules web.url, web.url.can-parse, web.url.parse, web.url.to-json, web.url-search-params, web.url-search-params.delete, web.url-search-params.has, web.url-search-params.size.
class URL {
constructor(url: string, base?: string);
attribute href: string;
readonly attribute origin: string;
attribute protocol: string;
attribute username: string;
attribute password: string;
attribute host: string;
attribute hostname: string;
attribute port: string;
attribute pathname: string;
attribute search: string;
readonly attribute searchParams: URLSearchParams;
attribute hash: string;
toJSON(): string;
toString(): string;
static canParse(url: string, base?: string): boolean;
static parse(url: string, base?: string): URL | null;
}
class URLSearchParams {
constructor(params?: string | Iterable<[key, value]> | Object);
append(name: string, value: string): void;
delete(name: string, value?: string): void;
get(name: string): string | void;
getAll(name: string): Array<string>;
has(name: string, value?: string): boolean;
set(name: string, value: string): void;
sort(): void;
toString(): string;
forEach(callbackfn: (value: any, index: number, target: any) => void, thisArg: any): void;
entries(): Iterator<[key, value]>;
keys(): Iterator<key>;
values(): Iterator<value>;
@@iterator(): Iterator<[key, value]>;
readonly attribute size: number;
}core-js/proposals/url
core-js(-pure)/stable|actual|full/url
core-js(-pure)/stable|actual|full/url/can-parse
core-js/stable|actual|full/url/to-json
core-js(-pure)/stable|actual|full/url-search-paramsURL.canParse('https://login:password@example.com:8080/?a=1&b=2&a=3&c=4#fragment'); // => true
URL.canParse('https'); // => false
URL.parse('https://login:password@example.com:8080/?a=1&b=2&a=3&c=4#fragment'); // => url
URL.parse('https'); // => null
const url = new URL('https://login:password@example.com:8080/foo/bar?a=1&b=2&a=3#fragment');
console.log(url.href); // => 'https://login:password@example.com:8080/foo/bar?a=1&b=2&a=3#fragment'
console.log(url.origin); // => 'https://example.com:8080'
console.log(url.protocol); // => 'https:'
console.log(url.username); // => 'login'
console.log(url.password); // => 'password'
console.log(url.host); // => 'example.com:8080'
console.log(url.hostname); // => 'example.com'
console.log(url.port); // => '8080'
console.log(url.pathname); // => '/foo/bar'
console.log(url.search); // => '?a=1&b=2&a=3'
console.log(url.hash); // => '#fragment'
console.log(url.toJSON()); // => 'https://login:password@example.com:8080/foo/bar?a=1&b=2&a=3#fragment'
console.log(url.toString()); // => 'https://login:password@example.com:8080/foo/bar?a=1&b=2&a=3#fragment'
for (let [key, value] of url.searchParams) {
console.log(key); // => 'a', 'b', 'a'
console.log(value); // => '1', '2', '3'
}
url.pathname = '';
url.searchParams.append('c', 4);
console.log(url.search); // => '?a=1&b=2&a=3&c=4'
console.log(url.href); // => 'https://login:password@example.com:8080/?a=1&b=2&a=3&c=4#fragment'
const params = new URLSearchParams('?a=1&b=2&a=3');
params.append('c', 4);
params.append('a', 2);
params.delete('a', 1);
params.sort();
console.log(params.size); // => 4
for (let [key, value] of params) {
console.log(key); // => 'a', 'a', 'b', 'c'
console.log(value); // => '3', '2', '2', '4'
}
console.log(params.has('a')); // => true
console.log(params.has('a', 3)); // => true
console.log(params.has('a', 4)); // => false
console.log(params.toString()); // => 'a=3&a=2&b=2&c=4'Caveats when using URL and URLSearchParams:⬆
- IE8 does not support setters, so they do not work on
URLinstances. However,URLconstructor can be used for basicURLparsing. - Legacy encodings in a search query are not supported. Also,
core-jsimplementation has some other encoding-related issues. URLimplementations from all of the popular browsers have much more problems thancore-js, however, replacing all of them does not looks like a good idea. You can customize the aggressiveness of polyfill by your requirements.
DOMException:⬆
The specification. Modules web.dom-exception.constructor, web.dom-exception.stack, web.dom-exception.to-string-tag.
class DOMException {
constructor(message: string, name?: string);
readonly attribute name: string;
readonly attribute message: string;
readonly attribute code: string;
attribute stack: string; // in engines that should have it
@@toStringTag: 'DOMException';
}core-js(-pure)/stable|actual|full/dom-exception
core-js(-pure)/stable|actual|full/dom-exception/constructor
core-js/stable|actual|full/dom-exception/to-string-tagconst exception = new DOMException('error', 'DataCloneError');
console.log(exception.name); // => 'DataCloneError'
console.log(exception.message); // => 'error'
console.log(exception.code); // => 25
console.log(typeof exception.stack); // => 'string'
console.log(exception instanceof DOMException); // => true
console.log(exception instanceof Error); // => true
console.log(exception.toString()); // => 'DataCloneError: error'
console.log(Object.prototype.toString.call(exception)); // => '[object DOMException]'Iterable DOM collections⬆
Some DOM collections should have iterable interface or should be inherited from Array. That means they should have forEach, keys, values, entries and @@iterator methods for iteration. So add them. Modules web.dom-collections.iterator and web.dom-collections.for-each.
class [
CSSRuleList,
CSSStyleDeclaration,
CSSValueList,
ClientRectList,
DOMRectList,
DOMStringList,
DataTransferItemList,
FileList,
HTMLAllCollection,
HTMLCollection,
HTMLFormElement,
HTMLSelectElement,
MediaList,
MimeTypeArray,
NamedNodeMap,
PaintRequestList,
Plugin,
PluginArray,
SVGLengthList,
SVGNumberList,
SVGPathSegList,
SVGPointList,
SVGStringList,
SVGTransformList,
SourceBufferList,
StyleSheetList,
TextTrackCueList,
TextTrackList,
TouchList,
] {
@@iterator(): Iterator<value>;
}
class [DOMTokenList, NodeList] {
forEach(callbackfn: (value: any, index: number, target: any) => void, thisArg: any): void;
entries(): Iterator<[key, value]>;
keys(): Iterator<key>;
values(): Iterator<value>;
@@iterator(): Iterator<value>;
}core-js(-pure)/stable|actual|full/dom-collections/iterator
core-js/stable|actual|full/dom-collections/for-eachfor (let { id } of document.querySelectorAll('*')) {
if (id) console.log(id);
}
for (let [index, { id }] of document.querySelectorAll('*').entries()) {
if (id) console.log(index, id);
}
document.querySelectorAll('*').forEach(it => console.log(it.id));Iteration helpers⬆
Helpers for check iterability / get iterator in the pure version or, for example, for arguments object:
function isIterable(value: any): boolean;
function getIterator(value: any): Object;
function getIteratorMethod(value: any): Function | void;core-js-pure/es|stable|actual|full/is-iterable
core-js-pure/es|stable|actual|full/get-iterator
core-js-pure/es|stable|actual|full/get-iterator-methodimport isIterable from 'core-js-pure/actual/is-iterable';
import getIterator from 'core-js-pure/actual/get-iterator';
import getIteratorMethod from 'core-js-pure/actual/get-iterator-method';
let list = (function () {
return arguments;
})(1, 2, 3);
console.log(isIterable(list)); // true;
let iterator = getIterator(list);
console.log(iterator.next().value); // 1
console.log(iterator.next().value); // 2
console.log(iterator.next().value); // 3
console.log(iterator.next().value); // undefined
getIterator({}); // TypeError: [object Object] is not iterable!
let method = getIteratorMethod(list);
console.log(typeof method); // 'function'
let iterator = method.call(list);
console.log(iterator.next().value); // 1
console.log(iterator.next().value); // 2
console.log(iterator.next().value); // 3
console.log(iterator.next().value); // undefined
console.log(getIteratorMethod({})); // undefinedMissing polyfills⬆
- ES
BigIntcan't be polyfilled since it requires changes in the behavior of operators, you could find more info here. You could try to useJSBI. - ES
Proxycan't be polyfilled, you can try to useproxy-polyfillwhich provides a very little subset of features. - ES
String#normalizeis not a very useful feature, but this polyfill will be very large. If you need it, you can use unorm. - ECMA-402
Intlis missed because of the size. You can use those polyfills. window.fetchis 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 might be added in the future. Now you can use, for example, this polyfill.