es-jest

library2.1.0jsnpmunverified

es-jest is a preprocessor for Jest that uses esbuild to transform ESM, React JSX, and TypeScript files. Version 2.1.0 (latest, last released in 2021) is stable but in maintenance mode. It offers faster transformation than babel-jest or ts-jest by leveraging esbuild, and supports custom esbuild configurations. It can be used as a Jest preset or via a transform entry. Note that major Jest version updates may break compatibility; v2 requires Jest 26+.

testing

npm install es-jest

github ↗package ↗

INSTALL

IMPORT

SIG · ES-JEST

es-jest

testingjavascriptv2.1.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

es-jest

✓ const esJest = require('es-jest')

✗ import esJest from 'es-jest'

This package is CJS only; dynamic import may work but require() is standard. Used as a transform processor, not directly invoked.

preset

✓ use in jest config: 'preset': 'es-jest'

✗ import { preset } from 'es-jest'

Preset is a string in Jest config, not an exported symbol.

transform

✓ use in jest config as ['es-jest', options]

✗ import { transform } from 'es-jest'

Transform is a config entry, not an import.

Demonstrates minimal setup via preset and a simple test using ES modules.

// jest.config.js module.exports = { preset: 'es-jest', // optional custom esbuild config: // transform: { // '\\.(js|ts|jsx|tsx)$': ['es-jest', { jsx: 'automatic' }] // } } // src/__tests__/example.test.js import { sum } from '../sum'; test('adds 1 + 2 to equal 3', () => { expect(sum(1, 2)).toBe(3); });

Debug

Known issues

deprecatedPackage has not been updated since 2021; may be incompatible with newer Jest versions (>27).

fix

Consider using jest-light-runner or @jest/transform-esbuild for ongoing support.

affects: >=2.1.0

gotchaWhen using custom transform entry, must escape regex or use string pattern correctly.

fix

Use double backslashes in JSON: '\\.(js|ts)x?$'

affects: >=2.0.0

gotchaes-jest does not support TypeScript type checking; it only strips types.

fix

Use ts-jest or run tsc separately for type safety.

affects: >=1.0.0

gotchaJSX automatic runtime requires esbuild >=0.14 and config option { jsx: 'automatic' }

fix

Ensure esbuild version meets requirements and pass options correctly.

affects: >=2.0.0

Errors

Common errors & fixes

Cannot find module 'es-jest' from 'jest.config.js'

es-jest is not installed

fix

Run 'npm install es-jest --save-dev'.

Jest preset "es-jest" not found.

Jest cannot find the preset; incorrect config file type (e.g., using ESM for config)

fix

Use module.exports in a .js config file, or ensure preset path is correct.

SyntaxError: Unexpected token 'export'

Jest not using es-jest transform; file is not transpiled

fix

Configure transform or preset in jest config. Add 'transform': { '\\.js$': 'es-jest' }

Error: Jest encountered an unexpected token. Jest failed to parse a file.

Missing babel-jest or incorrect transform for non-code files (e.g., CSS, images)

fix

Add appropriate moduleNameMapper or transformIgnorePatterns.

Upgrade

Version history

2.1.0latest on npm

Audit

Dependencies

jestrequiredPeer dependency required for usage

esbuildrequiredTranspilation engine

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/ambar/es-jest ↗

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