The core-js npm package is a modular standard library for JavaScript, which includes polyfills for ECMAScript features. It provides reliable polyfills to ensure that code behaves consistently across different environments, including older browsers.
Polyfilling ECMAScript features
This feature allows developers to use the latest ECMAScript features while ensuring backward compatibility with older environments that do not support these features natively.
require('core-js/stable');
// Now you can use ES6 features like Promise in environments that do not support them natively.Polyfilling Web Standards
Core-js can also polyfill web standards, allowing developers to use modern web APIs in environments that have not implemented them.
require('core-js/web');
// This includes polyfills for web standards like DOM collections (e.g., NodeList), timers, and more.Polyfilling Proposals
Developers can experiment with proposed ECMAScript features before they are finalized and adopted into the standard, ensuring forward compatibility.
require('core-js/proposals');
// This will include polyfills for ECMAScript proposals that are not yet part of the standard.Babel-polyfill is a package that provides polyfills necessary for a full ES2015+ environment. It is similar to core-js but is more tightly coupled with Babel's transpilation process.
The es6-shim package provides polyfills for ECMAScript 6 (aka ECMAScript 2015) features. It is similar to core-js but focuses specifically on ES6 features and does not cover proposals or web standards.
The polyfill-service by Financial Times is an online service that provides polyfills based on the user's browser. It is different from core-js in that it is a service rather than a package you include in your project, but it serves a similar purpose in polyfilling features.
Alternative standard library for javascript. Includes polyfills for ECMAScript 5, ECMAScript 6: Set, Map, WeakSet, WeakMap, Promise, Symbol, iterators; setImmediate, static array methods, console cap. Additional functionality: Dict, extended partial application, extended object api, Date formatting and other sugar.
npm i core-js
Browser:
<script src='core.min.js'></script>
Node.js:
require('core-js');
global -> object node
Object
.create(proto | null, descs?) -> object es5
.getPrototypeOf(object) -> proto | null es5 sham
.setPrototypeOf(object, proto | null) -> &0 es6 sham
.defineProperty(object, key, desc) -> &0 es5 sham
.defineProperties(object, descs) -> &0 es5 sham
.getOwnPropertyNames(object) -> array es5 sham
.getOwnPropertyDescriptor(object, key) -> desc es5
.keys(object) -> array es5
.values(object) -> array es7
.entries(object) -> array es7
.assign(target, ...src) -> &0 es6
.is(a, b) -> bool es6
.isPrototype(proto, object) -> bool core
.getOwnPropertyKeys(object) -> array core
.getPropertyDescriptor(object, key) -> desc core
.getOwnPropertyDescriptors(object) -> descs core
.make(proto | null, props?) -> object core
.define(object, props) -> &0 core
.isObject(var) -> bool core
.classof(var) -> string core
.tie(object, key, ...args | _) -> fn(...args) core
::[_](key, ...args | _) -> fn(...args) core
Function
::bind(object, ...args | _) -> fn(...args) es5
::part(...args | _) -> fn(...args) core
::by(object | _, ...args | _) -> fn(...args) core
::only(numberArguments, that /* = @ */) -> fn(...args) core
::methodize() -> fn(that, ...args) core
::invoke(args, that) -> var core
::construct(args) -> object core
::timeout(time, ...args) -> deferred core
::interval(time, ...args) -> deferred core
::immediate(...args) -> deferred core
Array
.isArray(var) -> bool es5
.from(iterable | array-like, fn(val, key, @)?, that) -> array es6
.of(...args) -> array es6
.{...Array::} js1.6
::slice(start?, end?) -> array es5
::join(string = ',') -> string es5
::indexOf(var, from?) -> int es5
::lastIndexOf(var, from?) -> int es5
::every(fn(val, key, @), that) -> bool es5
::some(fn(val, key, @), that) -> bool es5
::forEach(fn(val, key, @), that) -> void es5
::map(fn(val, key, @), that) -> array es5
::filter(fn(val, key, @), that) -> array es5
::reduce(fn(memo, val, key, @), memo?) -> var es5
::reduceRight(fn(memo, val, key, @), memo?) -> var es5
::fill(var, start?, end?) -> @ es5
::find(fn(val, key, @), that) -> var es6
::findIndex(fn(val, key, @), that) -> int es6
::values() -> iterator es6
::keys() -> iterator es6
::entries() -> iterator (entries) es6
::@@iterator() -> iterator es6
::get(index) -> var core
::set(index, value) -> @ core
::delete(index) -> bool core
::contains(var, from?) -> bool es7
::clone() -> var core
::turn(fn(memo, val, key, @), memo = []) -> memo core
[new] Dict(itarable (entries) | object ?) -> dict core
.isDict(var) -> bool core
.has(object, key) -> bool core
.get(object, key) -> val core
.set(object, key, value) -> &0 core
.forEach(object, fn(val, key, @), that) -> void core
.map(object, fn(val, key, @), that) -> new @ core
.filter(object, fn(val, key, @), that) -> new @ core
.some(object, fn(val, key, @), that) -> bool core
.every(object, fn(val, key, @), that) -> bool core
.find(object, fn(val, key, @), that) -> val core
.findKey(object, fn(val, key, @), that) -> key core
.keyOf(object, var) -> key core
.contains(object, var) -> bool core
.reduce(object, fn(memo, val, key, @), memo?) -> var core
.turn(object, fn(memo, val, key, @), memo = new @) -> memo core
.clone(foo) -> var core
new Set(iterable?) -> set es6
::add(key) -> @ es6
::clear() -> void es6
::delete(key) -> bool es6
::forEach(fn(el, el, @), that) -> void es6
::has(key) -> bool es6
::size -> uint es6
::values() -> iterator es6
::keys() -> iterator es6
::entries() -> iterator (entries) es6
::@@iterator() -> iterator es6
new Map(iterable (entries) ?) -> map es6
::clear() -> void es6
::delete(key) -> bool es6
::forEach(fn(val, key, @), that) -> void es6
::get(key) -> val es6
::has(key) -> bool es6
::set(key, val) -> @ es6
::size -> uint es6
::values() -> iterator es6
::keys() -> iterator es6
::entries() -> iterator (entries) es6
::@@iterator() -> iterator (entries) es6
new WeakSet(iterable?) -> weakset es6
::add(key) -> @ es6
::clear() -> void es6
::delete(key) -> bool es6
::has(key) -> bool es6
new WeakMap(iterable (entries) ?) -> weakmap es6 sham
::clear() -> void es6 sham
::delete(key) -> bool es6
::get(key) -> val es6
::has(key) -> bool es6
::set(key, val) -> @ es6
String
::trim() -> str es5
::contains(str, from?) -> bool es6
::startsWith(str, from?) -> bool es6
::endsWith(str, from?) -> bool es6
::repeat(num) -> str es6
::@@iterator() -> iterator es6 sham
::escapeHTML() -> str core
::unescapeHTML() -> str core
RegExp
.escape(str) -> str es7
Number
.EPSILON -> num es6
.isFinite(num) -> bool es6
.isInteger(num) -> bool es6
.isNaN(num) -> bool es6
.isSafeInteger(num) -> bool es6
.MAX_SAFE_INTEGER -> int es6
.MIN_SAFE_INTEGER -> int es6
.parseFloat(str) -> num es6
.parseInt(str) -> int es6
.toInteger(num) -> int core
::times(fn(i, i, @), that) -> array core
::random(lim = 0) -> num core
::{...Math} core
Math
.acosh(num) -> num es6
.asinh(num) -> num es6
.atanh(num) -> num es6
.cbrt(num) -> num es6
.clz32(num) -> uint es6
.cosh(num) -> num es6
.expm1(num) -> num es6
.hypot(...args) -> num es6
.imul(num, num) -> int es6
.log1p(num) -> num es6
.log10(num) -> num es6
.log2(num) -> num es6
.sign(num) -> 1 | -1 | 0 | -0 | NaN es6
.sinh(num) -> num es6
.tanh(num) -> num es6
.trunc(num) -> num es6
.randomInt(lim1, lim2 = 0) -> int core
Date
.now() -> int es5
.addLocale(key, object) -> @ core
.locale(key?) -> key core
::format(str, key?) -> str core
::formatUTC(str, key?) -> str core
Symbol(description?) -> symbol es6 sham
.for(key) -> symbol es6
.keyFor(symbol) -> key es6
.iterator -> symbol es6 sham
.toStringTag -> symbol es6
.pure() -> symbol || string core
.set(object, key, val) -> &0 core
new Promise(resolver(resolve(var), reject(var))) -> promise es6
::then(resolved(var), rejected(var)) -> promise es6
::catch(rejected(var)) -> promise es6
.resolve(var || promise) -> promise es6
.reject(var) -> promise es6
.all(iterable) -> promise es6
.race(iterable) -> promise es6
setTimeout(fn(...args), time, ...args) -> id w3c / whatwg
setInterval(fn(...args), time, ...args) -> id w3c / whatwg
setImmediate(fn(...args), ...args) -> id w3c / whatwg
clearImmediate(id) -> void w3c / whatwg
console(...args) -> void core
.{...console API} console api
.enable() -> void core
.disable() -> void core
$for(iterable, entries).of(fn(value, key?), that) -> void core
.isIterable(var) -> bool core
.getIterator(iterable) -> iterator core
core core
.{...global} core
_ -> object core / undescore
FAQs
Standard library
The npm package core-js receives a total of 29,062,431 weekly downloads. As such, core-js popularity was classified as popular.
We found that core-js demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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