ts-jest-resolver
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A resolver for `jest` that uses same strategy as TS when resolving files with JavaScript extension (".js").
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# ts-jest-resolver
[](https://travis-ci.org/VitorLuizC/ts-jest-resolver)
[](./LICENSE)
A resolver for [`jest`](https://jestjs.io/) that uses the same strategy as TS when resolving files with JavaScript extensions (".js", ".jsx", ".cjs" and ".mjs"). It works pretty well with [`ts-jest`](https://kulshekhar.github.io/ts-jest/) or [`babel`](https://babeljs.io/) with [`@babel/preset-typescript`](https://babeljs.io/docs/en/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](https://github.com/VitorLuizC/ts-jest-resolver/commit/a2cc8f6482250380c2c735bf8827eb64082d5ef6).
## Usage
This library is published in the NPM registry and can be installed using any compatible package manager.
```sh
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.
```js
// jest.config.js
module.exports = {
preset: "ts-jest",
resolver: "ts-jest-resolver",
};
```
## How it works
It changes module's extension to resolve in the same way as TypeScript.
### How it works with ".js" and ".jsx" extensions
When importing from path with JavaScript extension (".js" or ".jsx"):
```js
import EventEmitter from './EventEmitter.js';
```
1. It tries to resolve to a path with ".tsx";
```js
import EventEmitter from './EventEmitter.tsx';
```
2. If no file was found, it tries to resolve to a path with ".ts";
```js
import EventEmitter from './EventEmitter.ts';
```
3. If no file was found, it resolves to original path (with ".js" or ".jsx").
```js
import EventEmitter from './EventEmitter.js';
```
### How it works with ".mjs" and ".cjs" extensions
When importing from path with ES or CommonJS modules (".mjs" and ".cjs" respectively):
Ex.
```ts
import parse, { Tokenizer } from './parser.mjs'
import { discoverPath } from './getFiles.cjs';
```
1. It tries to resolve to paths with ".mts" and ".cts".
Ex.
```ts
import parse, { Tokenizer } from './parser.mts'
import { discoverPath } from './getFiles.cts';
```
2. If no files were found, it resolves to original paths (with ".mjs" and ".cjs").
Ex.
```ts
import parse, { Tokenizer } from './parser.mjs'
import { discoverPath } from './getFiles.cjs';
```
## License
Released under [MIT License](./LICENSE).