Registry / devops / babel-plugin-polyfill-corejs2

babel-plugin-polyfill-corejs2

library0.4.17jsnpmunverified

Babel plugin that automatically injects imports for core-js@2 polyfills based on language features used in the code. Current stable version is 0.4.17, released as part of the Babel polyfills project. Unlike manual core-js imports or @babel/polyfill, this plugin offers fine-grained control via methods like 'usage-global' (per-file polyfill injection into global scope), 'usage-pure' (pure expressions without side effects), and 'entry-global' (replaces core-js import entries). Requires @babel/core peer dependency. Development is focused on core-js@2 compatibility; for core-js@3 use babel-plugin-polyfill-corejs3.

devops

npm install babel-plugin-polyfill-corejs2

github ↗package ↗

INSTALL

IMPORT

SIG · BABEL-PLUGIN-POLYF

babel-plugin-polyfill-corejs2

devopsjavascriptv0.4.17

Install

—

Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

default

✓ import plugin from 'babel-plugin-polyfill-corejs2'; // In Babel config file (ESM)

✗ const plugin = require('babel-plugin-polyfill-corejs2'); // Works in CJS but not recommended for ESM-only projects

This is a Babel plugin, not typically imported directly; instead listed in .babelrc or babel.config.js as 'polyfill-corejs2' string or [require('babel-plugin-polyfill-corejs2'), options] in JS config.

Method options

✓ // In Babel config: { plugins: [['polyfill-corejs2', { method: 'usage-global' }]] }

✗ // Using invalid method: { plugins: [['polyfill-corejs2', { method: 'global' }]] }

Valid methods are 'usage-global', 'usage-pure', and 'entry-global'. Do not omit method or use a typo.

Programmatic usage

✓ import babel from '@babel/core'; import plugin from 'babel-plugin-polyfill-corejs2'; babel.transformSync(code, { plugins: [[plugin, { method: 'usage-pure' }]] });

✗ const babel = require('@babel/core'); const plugin = require('babel-plugin-polyfill-corejs2'); babel.transform(code, { plugins: [plugin] }); // Missing options or incorrect method

Must pass plugin options as an array; omitting options may default to 'usage-global' but explicit is safer.

Install the plugin and core-js@2 peer dependency. Note: core-js@2 is a required runtime dependency for polyfills.

npm install --save-dev babel-plugin-polyfill-corejs2 core-js@2 @babel/core

Debug

Known issues

deprecatedcore-js@2 is deprecated; consider migrating to core-js@3 and babel-plugin-polyfill-corejs3.

fix

Replace this plugin with babel-plugin-polyfill-corejs3 and core-js@3.

affects: >=0.0.0

gotchaThe plugin does not automatically install core-js; you must add core-js@2 as a dependency in your package.json.

fix

Run 'npm install core-js@2' or equivalent.

affects: >=0.0.0

breakingFrom version 0.2.0, the plugin replaces global core-js imports only when 'entry-global' method is used; prior versions defaulted differently.

fix

Update to 0.4.x and explicitly set method to 'entry-global' if you previously relied on global injection.

affects: <0.2.0

gotchaUsing 'usage-pure' method may cause polyfill duplication if multiple files use the same feature. Use 'usage-global' for single global polyfills.

fix

Select method carefully: 'usage-pure' for library development, 'usage-global' for applications.

affects: >=0.0.0

deprecatedThe 'entry-global' method replaces core-js entries but does not handle proposals; use @babel/plugin-proposal-* for proposals.

fix

Add corresponding proposal plugins (e.g., @babel/plugin-proposal-optional-chaining) alongside this plugin.

affects: >=0.0.0

Errors

Common errors & fixes

Cannot find module 'core-js'

core-js@2 not installed as a dependency.

fix

Install core-js@2: npm install core-js@2

Error: [BABEL] unknown: You gave us a visitor for the node type "ImportDeclaration" but it's not a valid type

Using incompatible version of @babel/core (older than 7.4.0).

fix

Update @babel/core to ^7.4.0.

ReferenceError: regeneratorRuntime is not defined

Plugin does not include regenerator-runtime; needed for async/await.

fix

Add @babel/plugin-transform-regenerator or manually import regenerator-runtime.

The 'entry-global' method did not inject any polyfills

No import statement for core-js found in the file; method expects an explicit import like 'import "core-js"'.

fix

Add 'import "core-js"' at the entry point of your application, or switch to 'usage-global' method.

Upgrade

Version history

0.4.17latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

6 hits · last 30 days

node

Resources

githubhttps://github.com/babel/babel-polyfills ↗

packagehttps://www.npmjs.com/package/babel-plugin-polyfill-corejs2 ↗