Supported engines

Browser and runtime support matrix for core-js, and how compatibility data is organized by module.

core-js aims to support all JS environments with ES3 support. Some features have a higher minimum bar — for example, certain accessors require ES5, and promises require a microtask or task scheduling mechanism.

Supported environments

core-js is tested against and supports the following engines:

Engine	Notes
Chrome	Fully supported
Firefox	Fully supported
Safari	Fully supported
Edge	Fully supported
Internet Explorer	IE 8+ supported; IE 8 does not support setters, so some APIs have limited behavior
Node.js	Fully supported; use 'current' as the version value to target the running version
Bun	Fully supported
Deno	Fully supported
Hermes	Fully supported
React Native	Fully supported (uses Hermes as default engine)
Electron	Fully supported
Rhino	Fully supported

Testing in IE7 and other very old engines has been discontinued. If you encounter issues with a specific engine, open an issue.

How compatibility data is organized

The core-js-compat package contains the full compatibility dataset. Data is keyed by module name and maps to an object of engine-to-version pairs. A version entry means that engine first gained a correct native implementation at that version — so core-js needs to polyfill that module for any target older than the listed version.

For example, this is what a slice of the raw data looks like:

// from core-js-compat/src/data.mjs
{
  'es.array.at': {
    chrome: '92',
    edge: '92',
    firefox: '90',
    safari: '15.4',
    node: '16.6.0',
  },
  'es.array.find-last': {
    chrome: '97',
    firefox: '104',
    safari: '15.4',
    node: '18.0.0',
  },
  'es.array.push': {
    chrome: '101',
    edge: '101',
    ios: '15.4',
    safari: '15.4',
  },
}

Module names follow the pattern <namespace>.<type>.<method>, where namespace is es for ECMAScript standard features, esnext for stage proposals, or web for web platform APIs.

Programmatic access via core-js-compat

The core-js-compat package exposes the full dataset and a compat() function that resolves which modules a given set of targets actually needs:

import compat from 'core-js-compat';

const { list, targets } = compat({
  targets: '> 1%',
});

console.log(list);
// => ['es.array.at', 'es.array.find-last', ...]

console.log(targets);
// => {
//   'es.array.at': { ios: '14.5-14.8' },
//   'es.array.find-last': { firefox: '100', ios: '14.5-14.8' },
//   ...
// }

You can also access the raw data directly:

const data = require('core-js-compat/data');
// => { [ModuleName]: { [EngineName]: EngineVersion } }

const modules = require('core-js-compat/modules');
// => Array<ModuleName>

const entries = require('core-js-compat/entries');
// => { [EntryPoint]: Array<ModuleName> }

core-js-compat package

Full API reference and dataset for programmatic compatibility queries.

Browserslist integration

How to use browserslist queries and target objects with core-js-compat.