babel-jest

library30.3.0jsnpmunverified

Jest plugin to use Babel for transformation of source files during testing. Current stable version is 30.3.0 (released 2025). It is part of the Jest monorepo and follows Jest's release cadence. Key differentiators: integrates tightly with Jest's transform pipeline, automatically picks up Babel configuration, supports custom transformers and presets, and is ESM-compatible. It is the recommended way to transpile modern JavaScript and TypeScript code in Jest tests when using Babel. Compared to alternative transformers like ts-jest, babel-jest is faster but does not perform type checking.

testing devops

npm install babel-jest

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · BABEL-JEST

babel-jest

testingjavascriptv30.3.0

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.

createTransformer

✓ import { createTransformer } from 'babel-jest'

✗ const { createTransformer } = require('babel-jest')

ESM-only since Jest 28; require() will fail in recent versions.

default (default export)

✓ import babelJest from 'babel-jest'

✗ const babelJest = require('babel-jest').default

Default export is the transformer object used in Jest config. Using require().default works in CJS but is not recommended.

TransformerConfig

✓ import type { TransformerConfig } from 'babel-jest'

✗ import { TransformerConfig } from 'babel-jest'

TransformerConfig is a type export only available from Jest 30.2.0. Use type import to avoid runtime error.

Configures babel-jest as the transformer for .js/.ts files in Jest, using createTransformer with custom Babel presets.

// jest.config.js import babelJest from 'babel-jest'; export default { transform: { '^.+\\.jsx?$': babelJest, '^.+\\.tsx?$': [ babelJest.createTransformer({ presets: [ ['@babel/preset-env', { targets: { node: 'current' } }], '@babel/preset-typescript', ], }), ], }, }; // Alternatively, use the createTransformer function with custom options. // This shows how to set up babel-jest for both JS and TS files.

Debug

Known issues

breakingbabel-jest is now ESM-only starting from Jest 28. Using require() will throw an error.

fix

Use import statements instead of require(). If you must use CommonJS, use dynamic import or upgrade your project to ESM.

affects: >=28

breakingIn Jest 30, the 'createTransformer' function returns a different object type. Some custom transform options may not work as before.

fix

Review the changelog for Jest 30 and update custom transformers accordingly.

affects: >=30

deprecatedThe default export (babelJest) is still supported but using createTransformer is preferred for explicit configuration.

fix

Replace usage of default export with createTransformer for clarity and future-proofing.

affects: >=28

gotchababel-jest does not perform type checking. It only strips types when using TypeScript. For type checking, use ts-jest or run tsc separately.

fix

Add a separate type check step in your CI or use the TypeScript compiler as a separate test.

affects: all

Errors

Common errors & fixes

Error: Jest: 'babel-jest' is not a valid transformer. Must be a function or an object with a 'process' method.

Using require() to import babel-jest in ESM-only mode, or misconfiguration in Jest transform.

fix

Ensure you are using import statements and that the transform is correctly set (e.g., use 'import babelJest from "babel-jest"').

Cannot find module '@babel/core' from 'babel-jest'

Missing required peer dependency @babel/core.

fix

Run 'npm install --save-dev @babel/core' or 'yarn add --dev @babel/core'.

TypeError: babelJest.createTransformer is not a function

Using an older version of babel-jest (pre-28) where createTransformer did not exist, or incorrect import.

fix

Upgrade to babel-jest v28+ and use 'import { createTransformer } from "babel-jest"'.

SyntaxError: Cannot use import statement outside a module

Using ESM syntax in a CommonJS file without proper .mjs extension or 'type' module in package.json.

fix

Add 'type': 'module' to package.json, or rename file to .mjs, or use require syntax for CJS.

Upgrade

Version history

30.3.0latest on npm

Audit

Dependencies

@babel/corerequiredPeer dependency required for Babel transformation.

Agent activity

15 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/jestjs/jest ↗

packagehttps://www.npmjs.com/package/babel-jest ↗

homepagehttps://jestjs.io/ ↗