babel-plugin-transform-replace-object-assign

2.0.0 verified Sat Apr 25 auth: no javascript deprecated

This Babel plugin replaces all `Object.assign` calls with a custom implementation specified via the `moduleSpecifier` option, importing the shim from an npm package. At version 2.0.0 (latest release, last updated in 2018), the plugin requires `@babel/core@^7.0.0` as a peer dependency. It is similar to `babel-plugin-transform-object-assign` but allows using an external package (e.g., `object-assign`) instead of Babel's internal `_extends` helper, reducing bundle size by avoiding per-file function declarations. However, the plugin is explicitly deprecated by the author: the original Chrome bug it addressed (V8 issue #4118) has been fixed since Chrome 49. The plugin remains functional but is discouraged for new projects; developers should consider native `Object.assign` or `babel-plugin-transform-object-assign` instead.

Common errors

error Error: Could not find plugin "transform-replace-object-assign". Ensure there is an entry in ./node_modules/babel-plugin-transform-replace-object-assign ↓

cause Plugin not installed or not listed correctly in Babel config.

fix

Run: npm install --save-dev babel-plugin-transform-replace-object-assign

error Error: Cannot find module 'object-assign' ↓

cause Default moduleSpecifier 'object-assign' not installed as a runtime dependency.

fix

Run: npm install --save object-assign

error TypeError: Object(...) is not a function (or similar at runtime if object-assign not imported properly) ↓

cause Plugin transforms code but the custom assign package is not available at runtime because it's only in devDependencies or missing.

fix

Ensure the moduleSpecifier package is in dependencies, not devDependencies.

Warnings

deprecated Plugin explicitly deprecated by author: original Chrome bug (V8 #4118) fixed in Chrome 49, making plugin unnecessary for its original purpose. Author advises against use unless you have a specific need. ↓

fix Use native Object.assign (ES6) or babel-plugin-transform-object-assign if you need runtime shimming.

gotcha The moduleSpecifier option must be a package available at runtime; if omitted, defaults to 'object-assign', which must be installed as a dependency. ↓

fix Ensure the specified package is in your dependencies and correct.

gotcha Plugin only replaces direct calls to Object.assign (e.g., Object.assign(a, b)) — not polyfills or re-assignments. Code that uses Object.assign as a value (e.g., var assign = Object.assign) will not be transformed. ↓

fix If you need to replace all uses, consider using a different approach like babel-plugin-transform-object-assign which uses the _extends helper.

breaking Major version 2.0.0 requires @babel/core ^7.0.0 (Babel 7) and is not compatible with Babel 6. ↓

fix If using Babel 6, stick with version 1.x of this plugin.

deprecated Plugin has not been updated since 2018 — no fix for potential future Babel core changes. ↓

fix Consider alternatives like babel-plugin-transform-object-assign or @babel/plugin-transform-object-assign (Babel 7 core).

Install

npm install babel-plugin-transform-replace-object-assign

yarn add babel-plugin-transform-replace-object-assign

pnpm add babel-plugin-transform-replace-object-assign

Imports

transform-replace-object-assign

wrong

plugins: ["transform-replace-object-assign"] (will use default moduleSpecifier, but may not be intended)

correct

plugins: [["transform-replace-object-assign", { "moduleSpecifier": "object-assign" }]]

Add to Babel config as a plugin; the option `moduleSpecifier` is optional and defaults to "object-assign". No direct JavaScript import needed.

object-assign (runtime package)
wrong
```
npm install --save-dev object-assign (should be regular dependency if used at runtime)
```
correct
```
npm install --save object-assign
```
The implementation package is imported at build time; ensure it is in dependencies.

object-assign (import in output)

wrong

import _objectAssign from 'object-assign'; (no common mistake, but output is auto-generated)

correct

import _objectAssign from 'object-assign';

Output uses ESM import; compatible with bundlers. No manual import required.

Quickstart

Install the plugin and a custom Object.assign implementation, configure Babel, and see how Object.assign is replaced with an import of the custom package.

// Install
npm install --save-dev @babel/core babel-plugin-transform-replace-object-assign
npm install --save object-assign

// .babelrc
{
  "plugins": [
    ["transform-replace-object-assign", { "moduleSpecifier": "object-assign" }]
  ]
}

// Input: src/index.js
Object.assign({}, { foo: 'bar' });

// Build output (after Babel transform):
import _objectAssign from 'object-assign';
_objectAssign({}, { foo: 'bar' });

// Note: Default option is { "moduleSpecifier": "object-assign" } so config can be simplified to:
{
  "plugins": ["transform-replace-object-assign"]
}