Registry / devops / metro-babel-register

metro-babel-register

library0.84.3jsnpmunverified

A babel/register configuration specifically for Metro, the JavaScript bundler for React Native. Version 0.84.3 is the latest stable release, with monthly releases on the Metro 0.84.x branch. It provides a pre-configured Babel require hook that enables on-the-fly transpilation of Node.js modules during Metro's build process. Key differentiators: it is deeply integrated with Metro's own Babel presets and plugins, ensuring compatibility with React Native's transform pipeline. Unlike generic `@babel/register`, this package automatically applies Metro's custom transforms and ignores, matching the bundler's internal behavior. It is designed for development-time use, typically in custom Metro plugins or scripts that need to evaluate source files with Babel. No external dependencies beyond @babel/register and @babel/core.

devops

npm install metro-babel-register

github ↗package ↗

INSTALL

IMPORT

SIG · METRO-BABEL-REGIST

metro-babel-register

devopsjavascriptv0.84.3

Install

—

Import

—

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.

metro-babel-register

✓ require('metro-babel-register')

✗ import 'metro-babel-register'

This package is intended for CommonJS require hook; ESM import may not work because it modifies Node's require.extensions before module evaluation. Use require() at the top of entry file.

✓ require('metro-babel-register').register()

✗ import { register } from 'metro-babel-register'

The module exports a function `register` that can be called to customize the hook. ESM import is not recommended; use require for side-effect hook.

default

✓ const metroBabelRegister = require('metro-babel-register'); metroBabelRegister();

✗ import metroBabelRegister from 'metro-babel-register'

The default export is a function that configures and applies the hook. Use require() to avoid ESM/CommonJS interop issues.

Shows how to require and configure metro-babel-register to enable on-the-fly transpilation for Node.js scripts, with example of overriding default Babel presets.

// Install: npm install --save-dev metro-babel-register // In your entry script (e.g., metro-plugin.js): require('metro-babel-register')({ // Optional: override babel config options ignore: [/node_modules/], // default ignores node_modules presets: ['@babel/preset-env'], plugins: ['@babel/plugin-transform-modules-commonjs'] }); // Now you can require files that use modern JS/JSX: const myModule = require('./path/to/component.jsx'); // Or simply use default behavior (no options): require('metro-babel-register'); const { App } = require('./App');

Debug

Known issues

breakingNode.js version requirements changed: v0.84.0 dropped support for Node v21, v23, and LTS minors before v20.19.

fix

Use Node >=20.19.4 (LTS) or >=22.x. Avoid Node v21, v23.

affects: >=0.84.0

gotchametro-babel-register modifies Node's require hook globally. This can interfere with other tools that rely on their own require hooks (e.g., ts-node or @babel/register).

fix

Only use in isolated scripts or ensure it is loaded after other hooks. Consider using it as the first require in your entry point.

affects: *

gotchaThe default ignore list excludes node_modules. If you need to transpile dependencies (e.g., for ES module interop), you must override the 'ignore' option.

fix

Provide an explicit `ignore` array that does not exclude the specific dependency, or set `ignore: []` to transpile everything.

affects: *

deprecatedUsing default export without options may be deprecated in future versions; prefer calling with explicit config object.

fix

Call `require('metro-babel-register')({ /* options */ })` even if empty object.

affects: >=0.84

Errors

Common errors & fixes

Error: Cannot find module '@babel/core'

Missing peer dependency @babel/core.

fix

npm install --save-dev @babel/core

require() of ES Module /path/to/file.mjs not supported

metro-babel-register does not handle native ESM files (.mjs). It only transpiles CommonJS modules.

fix

Use dynamic import() for .mjs files or convert to .js with CommonJS syntax.

TypeError: metro_babel_register is not a function

Using ESM import syntax (import ... from) which returns a module namespace object, not the function directly.

fix

Use require('metro-babel-register') instead of import, or use require('metro-babel-register').default() to get the function.

Upgrade

Version history

0.84.3latest on npm

Audit

Dependencies

@babel/registerrequiredCore peer dependency; provides the babel/register hook that can be configured with Metro's presets.

@babel/coreoptionalRequired by @babel/register; may need to be installed explicitly.

Agent activity

2 hits · last 30 days

node

Resources

githubhttps://github.com/facebook/metro ↗

packagehttps://www.npmjs.com/package/metro-babel-register ↗