ts-paths-transform

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A little helper transforming tsconfig paths to make jest config easier.

⚡ Install

``bash
yarn add -D ts-paths-transform
`

⚡ But why?

Grew tired of adding ts-jest just to use its pathsToModuleNameMapper function.

⚡ Scenario

Let's imagine I want to test a Typescript codebase using jest. I'm using paths like so:

👇 tsconfig.json

`json
{
[...]
"compilerOptions": {
"baseUrl": ".",
"paths": {
"@cool": ["src/cool/index.ts"],
"@api/": ["src/api/"]
}
}
}
`

Now in jest config, I could use the aforementioned pathsToModuleNameMapper function or set paths manually in moduleNameMapper:

👇 jest.config.ts

`typescript
const options: Config.InitialOptions = {
// [...]
moduleNameMapper: {
'^@cool$': 'src/cool/index.ts',
'^@api/(.*)$': 'src/api/$1',
},
transform: {
'^.+\\.[tj]sx?$': ['@swc/jest', {}],
},
};
`

Annoying 🥲

⚡ Using transformTsPaths function

Let's use the function this library exposes:

👇 jest.config.ts

`typescript
import { transformTsPaths } from ts-paths-transform;

import { compilerOptions } from './tsconfig.json';

const options: Config.InitialOptions = {
// [...]
moduleNameMapper: {
// [...]
...transformTsPaths(compilerOptions.paths)
},
transform: {
'^.+\\.[tj]sx?$': ['@swc/jest', {}],
},
};
`

$3

transformTsPaths accepts a second argument for options:

`typescript
const paths = transformTsPaths(compilerOptions.paths, {
prefix: 'blabla',
verbose: true,
});
`

#### 🧿 prefix - string

Prepends each path alias with a prefix:

`typescript
const tsConfigPaths = {
'@cool': ['src/cool/index.ts'],
'@api/': ['src/api/'],
};
const paths = transformTsPaths(tsConfigPaths, {
prefix: '/',
});

// Paths =
// '^@cool$': '/src/cool/index.ts',
// '^@api/(.*)$': '/src/api/$1',
`

#### 🧿 verbose - boolean

Displays transformed output:

`typescript
const tsConfigPaths = {
'@cool': ['src/cool/index.ts'],
'@api/': ['src/api/'],
};
const paths = transformTsPaths(tsConfigPaths, {
verbose: true,
});
`

👇 output:

`bash
ts-paths-transform 🚀 - 2 paths were found and transformed ✨
^@cool$: src/cool/index.ts
^@api/(.*)$: src/api/$1
``