babel-runtime

6.26.0 verified Sat Apr 25 auth: no javascript deprecated

babel-runtime is a self-contained runtime helper library for Babel-transpiled code, version 6.26.0. It provides polyfills and helpers (e.g., `classCallCheck`, `extends`, `typeof`) for ES6+ features without polluting the global scope. Unlike `@babel/runtime` (v7+), this is the legacy v6 package. It is stable but no longer actively developed; users should migrate to `@babel/runtime` v7+ for new projects. Key differentiator: bundling helpers at build time via `babel-plugin-transform-runtime` to avoid code duplication.

Common errors

error Cannot find module 'babel-runtime/core-js/object/keys' ↓

cause Missing dependency or incorrect import path.

fix

Ensure babel-runtime is installed and use correct path: require('babel-runtime/core-js/object/keys')

error TypeError: _classCallCheck is not a function ↓

cause Forgetting to append .default when requiring a helper.

fix

var _classCallCheck = require('babel-runtime/helpers/classCallCheck').default;

error Module not found: Can't resolve 'babel-runtime' ↓

cause babel-runtime not installed or listed in dependencies.

fix

npm install babel-runtime --save (or --save-dev for transform-runtime)

error Duplicate polyfill: core-js/modules/... ↓

cause Both babel-runtime and core-js are imported directly, causing duplication.

fix

Use only babel-runtime's polyfills or remove direct core-js imports.

Warnings

deprecated babel-runtime v6 is deprecated. Use @babel/runtime v7+ instead. ↓

fix Replace 'babel-runtime' with '@babel/runtime' and update plugins.

breaking In v6, helpers are CommonJS modules; importing them with ES import syntax may fail. ↓

fix Use require() or configure Babel to handle interop.

gotcha The default export is not available; always use named exports or .default property. ↓

fix Access helpers via require('babel-runtime/helpers/xyz').default

deprecated babel-plugin-transform-runtime v6 does not automatically resolve the correct helper vs polyfill; manual configuration needed. ↓

fix Use @babel/plugin-transform-runtime with @babel/runtime.

breaking core-js shims in babel-runtime are for v2 of core-js; mixing with core-js v3 causes conflicts. ↓

fix Use @babel/runtime-corejs2 or @babel/runtime-corejs3 instead.

Install

npm install babel-runtime

yarn add babel-runtime

pnpm add babel-runtime

Imports

default
wrong
```
import babelRuntime from 'babel-runtime'
```
correct
```
require('babel-runtime')
```
No default export; this module is used indirectly via Babel plugins.

helpers

wrong

import interopRequireDefault from 'babel-runtime/helpers/interopRequireDefault'

correct

var _interopRequireDefault = require('babel-runtime/helpers/interopRequireDefault').default;

Helpers are CommonJS modules; require the .default property or use Babel's transform-runtime plugin.

core-js/shims
wrong
```
import 'babel-runtime/core-js/object/keys'
```
correct
```
require('babel-runtime/core-js/object/keys');
```
Core-js shims are CommonJS modules and should be required, not imported, unless configured.

Quickstart

Shows how to install and use babel-runtime with transform-runtime plugin, requiring helpers and polyfills.

// Install: npm install babel-runtime babel-plugin-transform-runtime
// In .babelrc:
// { "plugins": ["transform-runtime"] }

// After build, helpers like _classCallCheck are automatically required:
var _classCallCheck = require('babel-runtime/helpers/classCallCheck')['default'];

function MyClass() {
  _classCallCheck(this, MyClass);
}

// Use core-js polyfills:
var keys = require('babel-runtime/core-js/object/keys');
var obj = {a: 1, b: 2};
console.log(keys(obj)); // ['a', 'b']