ts-jest-resolver

A resolver for jest that uses the same strategy as TS when resolving files with JavaScript extensions (".js", ".cjs" and ".mjs"). It works pretty well with ts-jest or babel with @babel/preset-typescript.

• 📦 Distributions in ESM and CommonJS.
  • Supports both Node.js ESM (import/export) and CommonJS (require/module.exports).
• ⚡ Lightweight:
  • It's bundled using rollup.js.
• 🔋 Bateries included:
  • It just depends on jest-resolver types.
• ✅ Safe:
  • Made with ESLint, TypeScript as strict as possible.
  • Unit tests with Jest.
  • Like ts-jest, ts-jest-resolver uses itself as jest's resolver.

Usage

This library is published in the NPM registry and can be installed using any compatible package manager.

npm install ts-jest-resolver --save

# For Yarn, use the command below.
yarn add ts-jest-resolver

After installation, you can set "ts-jest-resolver" as jest's resolver.

// jest.config.js

module.exports = {
  preset: "ts-jest",
  resolver: "ts-jest-resolver",
};

How it works

It just changes module resolution when the import statement has ".js" extension:

Ex.

import EventEmitter from './EventEmitter.js';

1. It tries to resolve the import path with ".ts" instead of ".js".

   Ex.

   import EventEmitter from './EventEmitter.ts';

2. If the module wasn't found, it tries to resolve the import path with ".tsx" instead of ".js".

   Ex.

   import EventEmitter from './EventEmitter.tsx';

3. If the module wasn't found, it resolves to the original import path (with ".js").

   Ex.

   import EventEmitter from './EventEmitter.js';

It does the same for ".cts" and ".mts" extensions.

Ex.

import * as colors from './colors.mjs'
import { discoverPath } from './getFiles.cjs';

1. It tries to resolve the import path with ".mts" and ".cts" instead of ".mjs" and ".cjs".

   Ex.

   import * as colors from './colors.mts'
   import { discoverPath } from './getFiles.cts';

2. If the module wasn't found, it resolves to the original import paths (with ".mjs" and ".cjs").

   Ex.

   import * as colors from './colors.mjs'
   import { discoverPath } from './getFiles.cjs';

License

Released under MIT License.