idempotent-babel-polyfill

7.4.4 verified Sat Apr 25 auth: no javascript maintenance

A tiny utility that allows importing babel-polyfill multiple times without causing duplicate initialization errors. Version 7.4.4 is the latest stable release; the package has seen no updates since 2018 and effectively acts as a polyfill wrapper for legacy Babel setups. It provides an idempotent import that checks if core-js or regenerator-runtime has already been loaded, preventing multiple polyfill application which can cause conflicts and performance issues. Unlike directly importing babel-polyfill, this package is safe to include in library code where consumers may also polyfill.

Common errors

error Error: Cannot find module 'babel-polyfill' ↓

cause babel-polyfill is not installed as a dependency.

fix

npm install babel-polyfill

error Attempted to load multiple Babel polyfills, which may cause issues. ↓

cause Multiple imports of babel-polyfill in the same application.

fix

Use idempotent-babel-polyfill to safely import only once.

error Requested path: babel-polyfill not found in module map ↓

cause Using idempotent-babel-polyfill in an environment where babel-polyfill is not available.

fix

Install babel-polyfill as a direct dependency.

Warnings

deprecated babel-polyfill is deprecated in favor of core-js/stable and regenerator-runtime/runtime. ↓

fix Replace with direct imports: import 'core-js/stable'; import 'regenerator-runtime/runtime';

breaking Package hasn't been updated since 2018; may be incompatible with modern Babel 7.4+. ↓

fix Use core-js directly or @babel/preset-env with useBuiltIns.

gotcha Importing idempotent-babel-polyfill multiple times still loads babel-polyfill once, but babel-polyfill itself may cause duplicate if already present. ↓

fix Ensure no other polyfill is loaded before this import.

gotcha The package does not guarantee idempotency if used in bundled environments with multiple copies. ↓

fix Use dedupe tools or better: use core-js directly with proper configuration.

Install

npm install idempotent-babel-polyfill

yarn add idempotent-babel-polyfill

pnpm add idempotent-babel-polyfill

Imports

default import (side-effect)
wrong
```
import idempotentBabelPolyfill from 'idempotent-babel-polyfill'
```
correct
```
import 'idempotent-babel-polyfill'
```
The default import is a side-effect import that loads and executes the polyfill; named exports require object destructuring.

idempotentBabelPolyfill

wrong

import idempotentBabelPolyfill from 'idempotent-babel-polyfill'

correct

import { idempotentBabelPolyfill } from 'idempotent-babel-polyfill'

The named export is a function that triggers the polyfill manually; it is not the default export.

require
```
require('idempotent-babel-polyfill')
```
CJS require works fine; no need for destructuring. The package supports both ESM and CJS.

Quickstart

Shows three ways to use the package: side-effect import, require, and calling the exported function.

// Install: npm install idempotent-babel-polyfill

// Option 1: Import as side-effect (recommended)
import 'idempotent-babel-polyfill';

// Option 2: Use require
require('idempotent-babel-polyfill');

// Option 3: Call the exported function manually
import { idempotentBabelPolyfill } from 'idempotent-babel-polyfill';
idempotentBabelPolyfill();