babel-helper-modules

6.0.0 verified Sat Apr 25 auth: no javascript

Provides Babel's internal helper functions (like _classCallCheck, _extends, etc.) as individual ES5 modules that can be imported directly. Version 6.0.0 is the latest stable release. Unlike babel-runtime which bundles core-js, this package avoids core-js dependencies, giving users freedom to choose their own polyfill (e.g., @babel/polyfill). Designed to be used with babel-plugin-transform-helper-modules to replace helper calls with direct imports, reducing bundle size and avoiding duplicate helper code. Supports only CommonJS require syntax and is intended for Node/Babel build pipelines.

Common errors

error SyntaxError: Cannot use import statement outside a module ↓

cause Trying to use ES import syntax with a CommonJS-only package.

fix

Change to var helper = require('babel-helper-modules').helperName;

error TypeError: _classCallCheck is not a function ↓

cause Incorrectly accessing the helper (e.g., importing default instead of named).

fix

Ensure you use require('babel-helper-modules').classCallCheck and not require('babel-helper-modules') alone.

error Uncaught SyntaxError: Unexpected token 'extends' ↓

cause Variable name 'extends' is reserved; using it as a variable name without renaming.

fix

Rename the imported helper: var _extends = require('babel-helper-modules').extends;

error Module not found: Error: Can't resolve 'babel-helper-modules' ↓

cause Package not installed or missing from node_modules.

fix

Run npm install babel-helper-modules --save or yarn add babel-helper-modules.

Warnings

gotcha Package is CommonJS-only; ESM import patterns (import/export) will fail. Only use require(). ↓

fix Use `var helper = require('babel-helper-modules').helperName;` instead of `import`.

gotcha The helper name 'extends' must be aliased when assigning because 'extends' is a reserved word in JavaScript. ↓

fix Assign to a different variable name: `var _extends = require('babel-helper-modules').extends;`

deprecated This package is a legacy artifact from Babel 6 era. Babel 7 uses @babel/helpers and @babel/runtime. New projects should prefer @babel/runtime with appropriate transform plugin. ↓

fix Migrate to @babel/runtime and @babel/plugin-transform-runtime for Babel 7+.

gotcha No TypeScript type definitions are provided. Using this package in a TypeScript project will require manual type declarations. ↓

fix Create a custom .d.ts file or use `require` with `@ts-ignore`.

gotcha Package does not include core-js polyfills; you must provide your own polyfill (e.g., @babel/polyfill) for instance methods like Array.prototype.find. ↓

fix Add @babel/polyfill or core-js to your project and import it early.

Install

npm install babel-helper-modules

yarn add babel-helper-modules

pnpm add babel-helper-modules

Imports

classCallCheck

wrong

import { classCallCheck } from 'babel-helper-modules';

correct

var classCallCheck = require('babel-helper-modules').classCallCheck;

This package does not ship ESM; only CommonJS require is supported.

extends
wrong
```
import extends from 'babel-helper-modules';
```
correct
```
var _extends = require('babel-helper-modules').extends;
```
The helper name 'extends' conflicts with a JavaScript reserved word; assign to a different variable.

objectWithoutProperties

wrong

import { objectWithoutProperties } from 'babel-helper-modules';

correct

var objectWithoutProperties = require('babel-helper-modules').objectWithoutProperties;

CommonJS only; no default export.

Quickstart

Shows importing and using multiple Babel helper modules from the package, demonstrating classCallCheck, inherits, extends, objectWithoutProperties, and possibleConstructorReturn.

var classCallCheck = require('babel-helper-modules').classCallCheck;
var inherits = require('babel-helper-modules').inherits;
var extendsHelper = require('babel-helper-modules').extends;
var objectWithoutProperties = require('babel-helper-modules').objectWithoutProperties;
var possibleConstructorReturn = require('babel-helper-modules').possibleConstructorReturn;

// Example usage
function Child() {
  classCallCheck(this, Child);
  var self = possibleConstructorReturn(this, (Child.__proto__ || Object.getPrototypeOf(Child)).call(this));
  return self;
}
inherits(Child, Parent);
var _ref = someObject;
var a = _ref.a;
var rest = objectWithoutProperties(_ref, ['a']);
var newObj = extendsHelper({}, rest, { b: 2 });