core-js-compat

What is core-js-compat?

The core-js-compat package provides compatibility data for core-js, which is a modular standard library for JavaScript, including polyfills for ECMAScript up to the latest standards. It is useful for developers who need to know which features are available in core-js for a specific version of a browser or Node.js.

What are core-js-compat's main functionalities?

Compatibility Data Retrieval

Retrieve a list of features supported by core-js for a specific environment, such as Chrome 70.

const { list } = require('core-js-compat')({ targets: 'chrome 70' });

Custom Build Generation

Generate a list of core-js modules required to support a specific target, such as Internet Explorer 11, with a specific version of core-js.

const { getModulesListForTargetVersion } = require('core-js-compat');
const modulesList = getModulesListForTargetVersion({ targets: { ie: 11 }, version: '3.6' });

Other packages similar to core-js-compat

babel-polyfill

Babel-polyfill is a package that includes Babel transforms and a polyfill that includes a custom regenerator runtime and core-js. It is similar to core-js-compat in that it provides polyfills for ECMAScript features, but it is less modular and is deprecated in favor of directly including core-js and regenerator-runtime.

es6-shim

The es6-shim package provides polyfills for ECMAScript 6 (also known as ECMAScript 2015) features. It is similar to core-js-compat in providing polyfills, but it is focused only on ES6 features and does not provide the modular approach or the compatibility data that core-js-compat offers.

polyfill-service

The polyfill-service package by Financial Times provides a service that returns a set of polyfills based on the user-agent string of the browser making the request. It is similar to core-js-compat in that it aims to provide polyfills for compatibility, but it does so as a service rather than a package to include in your project.

README

core-js-compat package contains data about the necessity of core-js modules and API for getting a list of required core-js modules by browserslist query.

const {
  list,                  // array of required modules
  targets,               // object with targets for each module
} = require('core-js-compat')({
  targets: '> 2.5%',     // browserslist query or object of minimum environment versions to support
  filter: /^(es|web)\./, // optional filter - string-prefix, regexp or list of modules
  version: '3.17',       // used `core-js` version, by default - the latest
});

console.log(targets);
/* =>
{
  'es.symbol.match-all': { ios: '12.2-12.4' },
  'es.array.unscopables.flat': { ios: '12.2-12.4' },
  'es.array.unscopables.flat-map': { ios: '12.2-12.4' },
  'es.math.hypot': { chrome: '77' },
  'es.promise.all-settled': { firefox: '69', ios: '12.2-12.4' },
  'es.promise.finally': { ios: '12.2-12.4' },
  'es.string.match-all': { chrome: '77', firefox: '69', ios: '12.2-12.4' },
  'es.string.replace': { firefox: '69', ios: '12.2-12.4' },
  'es.typed-array.float32-array': { ios: '12.2-12.4' },
  'es.typed-array.float64-array': { ios: '12.2-12.4' },
  'es.typed-array.int8-array': { ios: '12.2-12.4' },
  'es.typed-array.int16-array': { ios: '12.2-12.4' },
  'es.typed-array.int32-array': { ios: '12.2-12.4' },
  'es.typed-array.uint8-array': { ios: '12.2-12.4' },
  'es.typed-array.uint8-clamped-array': { ios: '12.2-12.4' },
  'es.typed-array.uint16-array': { ios: '12.2-12.4' },
  'es.typed-array.uint32-array': { ios: '12.2-12.4' },
  'es.typed-array.from': { ios: '12.2-12.4' },
  'es.typed-array.of': { ios: '12.2-12.4' },
  'web.dom-collections.iterator': { ios: '12.2-12.4' },
  'web.immediate': { chrome: '77', firefox: '69', ios: '12.2-12.4' },
  'web.url': { ios: '12.2-12.4' },
  'web.url.to-json': { ios: '12.2-12.4' },
  'web.url-search-params': { ios: '12.2-12.4' }
}
*/

targets option

targets could be a browserslist query or a targets object that specifies minimum environment versions to support:

// browserslist query:
'defaults, not IE 11, maintained node versions'
// object:
{
  android: '4.0',      // Android WebView version
  chrome: '38',        // Chrome version
  deno: '1.12',        // Deno version
  edge: '13',          // Edge version
  electron: '5.0',     // Electron framework version
  firefox: '15',       // Firefox version
  ie: '8',             // Internet Explorer version
  ios: '13.0',         // iOS Safari version
  node: 'current',     // NodeJS version, you could use 'current' for set it to currently used
  opera: '12',         // Opera version
  opera_mobile: '7',   // Opera Mobile version
  phantom: '1.9',      // PhantomJS headless browser version
  rhino: '1.7.13',     // Rhino engine version
  safari: '14.0',      // Safari version
  samsung: '14.0',     // Samsung Internet version
  esmodules: true,     // That option set target to minimum supporting ES Modules versions of all browsers
  browsers: '> 0.25%', // Browserslist query or object with target browsers
}

Additional API:

// equals of of the method from the example above
require('core-js-compat/compat')({ targets, filter, version }); // => { list: Array<ModuleName>, targets: { [ModuleName]: { [EngineName]: EngineVersion } } }
// or
require('core-js-compat').compat({ targets, filter, version }); // => { list: Array<ModuleName>, targets: { [ModuleName]: { [EngineName]: EngineVersion } } }

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

// map of modules by `core-js` entry points:
require('core-js-compat/entries'); // => { [EntryPoint]: Array<ModuleName> }
// or
require('core-js-compat').entries; // => { [EntryPoint]: Array<ModuleName> }

// full list of modules:
require('core-js-compat/modules'); // => Array<ModuleName>
// or
require('core-js-compat').modules; // => Array<ModuleName>

// the subset of modules which available in the passed `core-js` version:
require('core-js-compat/get-modules-list-for-target-version')('3.17'); // => Array<ModuleName>
// or
require('core-js-compat').getModulesListForTargetVersion('3.17'); // => Array<ModuleName>

If you want to add new / update data about modules required for target engines, follow this instruction.

Changelog

3.17.3 - 2021.09.09

• Fixed some possible problems related to possible extension of %IteratorPrototype% and %AsyncIteratorPrototype% in the future
• Fixed DOMTokenList.prototype.{ forEach, @@iterator, keys, values, entries } in old WebKit versions where element.classList is not an instance of global DOMTokenList
• Added NodeJS 16.9 compat data mapping
• Added Samsung Internet 16.0 compat data mapping