jest-esbuild

0.4.0 verified Mon Apr 27 auth: no javascript maintenance

A Jest transformer that uses esbuild to compile TypeScript/JavaScript files during test execution. Current stable version is 0.4.0, released in 2021 with no recent updates (maintenance mode). It provides fast compilation by leveraging esbuild's speed, significantly faster than ts-jest. It requires Jest 27+ and supports ESM/CJS via esbuild's loader. Key differentiator: minimal configuration and speed compared to ts-jest or babel-jest. Not recommended for projects needing type checking, as esbuild strips types without validation.

Common errors

error TypeError: (0 , _jestEsbuild.createTransformer) is not a function ↓

cause Incorrect import of named export; using default import for createTransformer.

fix

Use require('jest-esbuild').createTransformer or import { createTransformer } from 'jest-esbuild'.

error Error: jest-esbuild: Expected a jest version >= 27 ↓

cause Jest version < 27 is used.

fix

Upgrade Jest to 27 or later.

error SyntaxError: Unexpected token < ↓

cause JSX files not transformed; missing loader configuration.

fix

Add options: { loaders: { '.tsx': 'tsx' } } in transform array.

Warnings

gotcha jest-esbuild does not type-check; it only transforms code. Type errors will be ignored, potentially masking bugs. ↓

fix Run tsc separately or add type checking step in CI.

deprecated jest-esbuild is no longer actively maintained. Consider alternatives like @swc/jest or esbuild-jest. ↓

fix Migrate to @swc/jest (recommended) or esbuild-jest.

gotcha Options for esbuild are not well documented; configuration errors can cause silent failures. ↓

fix Refer to esbuild API docs; use known options like 'loader', 'jsxFactory', 'target'.

breaking Version 0.4.0 changed from default export to named export? (Unconfirmed breaking change anecdotal) ↓

fix If using createTransformer, verify import path; recommended: use string transformer in config.

Install

npm install jest-esbuild

yarn add jest-esbuild

pnpm add jest-esbuild

Imports

jest-esbuild (default)

wrong

transform: {
  '^.+\\.tsx?$': ['jest-esbuild', {}]
}

correct

module.exports = {
  transform: {
    '^.+\\.tsx?$': 'jest-esbuild'
  }
}

Correct usage in jest config; options object is not required but can be passed as second element in array.

jest-esbuild (with options)

wrong

transform: {
  '^.+\\.tsx?$': 'jest-esbuild',
  esbuildOptions: { loaders: { '.js': 'jsx' } }
}

correct

module.exports = {
  transform: {
    '^.+\\.tsx?$': ['jest-esbuild', { loaders: { '.js': 'jsx' } }]
  }
}

Options must be inline in array, not separate field.

createTransformer (named export)

wrong

const createTransformer = require('jest-esbuild');

correct

const { createTransformer } = require('jest-esbuild');
module.exports = { transform: { '^.+\\.tsx?$': createTransformer() } };

Export is named; default export is the transformer itself in CJS but named export exists.

Quickstart

Basic setup to transform .ts/.tsx files with jest-esbuild; test file written in TypeScript.

// Install: npm install -D jest-esbuild
// jest.config.js
module.exports = {
  transform: {
    '^.+\\.tsx?$': 'jest-esbuild'
  }
};

// Example test (sum.test.ts)
const sum = (a: number, b: number) => a + b;
test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});