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https://github.com/dividab/tsconfig-paths

Load node modules according to tsconfig paths, in run-time or via API.
https://github.com/dividab/tsconfig-paths

tsconfig tsconfig-paths typescript

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Load node modules according to tsconfig paths, in run-time or via API.

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# tsconfig-paths



[![npm version][version-image]][version-url]

[![build][build-image]][build-url]

[![Coverage Status][codecov-image]][codecov-url]

[![MIT license][license-image]][license-url]

[![code style: prettier][prettier-image]][prettier-url]



Use this to load modules whose location is specified in the `paths` section of `tsconfig.json` or `jsconfig.json`. Both loading at run-time and via API are supported.



Typescript by default mimics the Node.js runtime resolution strategy of modules. But it also allows the use of [path mapping](https://www.typescriptlang.org/docs/handbook/module-resolution.html) which allows arbitrary module paths (that doesn't start with "/" or ".") to be specified and mapped to physical paths in the filesystem. The typescript compiler can resolve these paths from `tsconfig` so it will compile OK. But if you then try to execute the compiled files with node (or ts-node), it will only look in the `node_modules` folders all the way up to the root of the filesystem and thus will not find the modules specified by `paths` in `tsconfig`.



If you require this package's `tsconfig-paths/register` module it will read the `paths` from `tsconfig.json` or `jsconfig.json` and convert node's module loading calls to physical file paths that node can load.



## How to install



```

yarn add --dev tsconfig-paths

```



or



```

npm install --save-dev tsconfig-paths

```



## How to use



### With node



`node -r tsconfig-paths/register main.js`



If `process.env.TS_NODE_BASEURL` is set it will override the value of `baseUrl` in tsconfig.json:



`TS_NODE_BASEURL=./dist node -r tsconfig-paths/register main.js`



### With ts-node



`ts-node -r tsconfig-paths/register main.ts`



If `process.env.TS_NODE_PROJECT` is set it will be used to resolved tsconfig.json



### With webpack



For webpack please use the [tsconfig-paths-webpack-plugin](https://github.com/dividab/tsconfig-paths-webpack-plugin).



### With mocha and ts-node



As of Mocha >= 4.0.0 the `--compiler` was [deprecated](https://github.com/mochajs/mocha/wiki/compilers-deprecation). Instead `--require` should be used. You also have to specify a glob that includes `.ts` files because mocha looks after files with `.js` extension by default.



```bash

mocha -r ts-node/register -r tsconfig-paths/register "test/**/*.ts"

```



### With other commands



As long as the command has something similar to a `--require` option that can load a module before it starts, tsconfig-paths should be able to work with it.



### With `ts-node` and VSCode



The following is an example configuration for the `.vscode/launch.json`.



```js

{

  "version": "0.2.0",

  "configurations": [

    {

      "name": "Debug Functions",

      "request": "launch",

      "type": "node",

      "runtimeArgs": [

        "-r",

        "${workspaceFolder}/functions/node_modules/ts-node/register",

        "-r",

        "${workspaceFolder}/functions/node_modules/tsconfig-paths/register"

      ],

      "args": ["${workspaceFolder}/functions/src/index.ts"],

      "cwd": "${workspaceFolder}",

      "protocol": "inspector",

      "env": {

        "NODE_ENV": "development",

        "TS_NODE_PROJECT": "${workspaceFolder}/functions/tsconfig.json"

      },

      "outFiles": ["${workspaceFolder}/functions/lib/**/*.js"]

    }

  ]

}

```



## Bootstrapping with explicit params



If you want more granular control over tsconfig-paths you can bootstrap it. This can be useful if you for instance have compiled with `tsc` to another directory where `tsconfig.json` doesn't exists.



For example, create a wrapper script called `tsconfig-paths-bootstrap.js` with the contents below:



```javascript

const tsConfig = require("./tsconfig.json");

const tsConfigPaths = require("tsconfig-paths");



const baseUrl = "./"; // Either absolute or relative path. If relative it's resolved to current working directory.

const cleanup = tsConfigPaths.register({

  baseUrl,

  paths: tsConfig.compilerOptions.paths,

});



// When path registration is no longer needed

cleanup();

```



Then run with:



`node -r ./tsconfig-paths-bootstrap.js main.js`



## Configuration Options



You can set options by passing them before the script path, via programmatic usage or via environment variables.



```bash

ts-node --project customLocation/tsconfig.json -r tsconfig-paths/register "test/**/*.ts"

```



### CLI and Programmatic Options



_Environment variable denoted in parentheses._



- `-P, --project [path]` Path to TypeScript JSON project file (`TS_NODE_PROJECT`)



## Config loading process



1.  Use explicit params passed to register

2.  Use `process.env.TS_NODE_PROJECT` to resolve tsConfig.json and the specified baseUrl and paths.

3.  Resolves tsconfig.json from current working directory and the specified baseUrl and paths.



## Programmatic use



The public API consists of these functions:



- [register](#register)

- [loadConfig](#loadConfig)

- [createMatchPath](#createMatchPath) / [createMatchPathAsync](#createMatchPathAsync)

- [matchFromAbsolutePaths](#matchFromAbsolutePaths) / [matchFromAbsolutePathsAsync](#matchFromAbsolutePathsAsync)



### register



```typescript

export interface ExplicitParams {

  baseUrl: string;

  paths: { [key: string]: Array };

  mainFields?: (string | string[])[];

  addMatchAll?: boolean;

  cwd?: string;

}



/**

 * Installs a custom module load function that can adhere to paths in tsconfig.

 */

export function register(explicitParams: ExplicitParams): () => void;

```



This function will patch the node's module loading so it will look for modules in paths specified by `tsconfig.json` or `jsconfig.json`.

A function is returned for you to reinstate Node's original module loading.



### loadConfig



```typescript

export function loadConfig(cwd: string = process.cwd()): ConfigLoaderResult;



export type ConfigLoaderResult =

  | ConfigLoaderSuccessResult

  | ConfigLoaderFailResult;



export interface ConfigLoaderSuccessResult {

  resultType: "success";

  absoluteBaseUrl: string;

  paths: { [key: string]: Array };

}



export interface ConfigLoaderFailResult {

  resultType: "failed";

  message: string;

}

```



This function loads the `tsconfig.json` or `jsconfig.json`. It will start searching from the specified `cwd` directory. Passing the `tsconfig.json` or `jsconfig.json` file directly instead of a directory also works.



### createMatchPath



```typescript

/**

 * Function that can match a path

 */

export interface MatchPath {

  (

    requestedModule: string,

    readJson?: Filesystem.ReadJsonSync,

    fileExists?: (name: string) => boolean,

    extensions?: ReadonlyArray

  ): string | undefined;

}



/**

 * Creates a function that can resolve paths according to tsconfig paths property.

 * @param absoluteBaseUrl Absolute version of baseUrl as specified in tsconfig.

 * @param paths The paths as specified in tsconfig.

 * @param mainFields A list of package.json field names to try when resolving module files. Select a nested field using an array of field names.

 * @param addMatchAll Add a match-all "*" rule if none is present

 * @returns a function that can resolve paths.

 */

export function createMatchPath(

  absoluteBaseUrl: string,

  paths: { [key: string]: Array },

  mainFields: (string | string[])[] = ["main"],

  addMatchAll: boolean = true

): MatchPath {

```



The `createMatchPath` function will create a function that can match paths. It accepts `baseUrl` and `paths` directly as they are specified in tsconfig and will handle resolving paths to absolute form. The created function has the signature specified by the type `MatchPath` above.



### matchFromAbsolutePaths



```typescript

/**

 * Finds a path from tsconfig that matches a module load request.

 * @param absolutePathMappings The paths to try as specified in tsconfig but resolved to absolute form.

 * @param requestedModule The required module name.

 * @param readJson Function that can read json from a path (useful for testing).

 * @param fileExists Function that checks for existence of a file at a path (useful for testing).

 * @param extensions File extensions to probe for (useful for testing).

 * @param mainFields A list of package.json field names to try when resolving module files. Select a nested field using an array of field names.

 * @returns the found path, or undefined if no path was found.

 */

export function matchFromAbsolutePaths(

  absolutePathMappings: ReadonlyArray,

  requestedModule: string,

  readJson: Filesystem.ReadJsonSync = Filesystem.readJsonFromDiskSync,

  fileExists: Filesystem.FileExistsSync = Filesystem.fileExistsSync,

  extensions: Array = Object.keys(require.extensions),

  mainFields: (string | string[])[] = ["main"]

): string | undefined {

```



This function is lower level and requires that the paths as already been resolved to absolute form and sorted in correct order into an array.



### createMatchPathAsync



This is the async version of `createMatchPath`. It has the same signature but with a callback parameter for the result.



### matchFromAbsolutePathsAsync



This is the async version of `matchFromAbsolutePaths`. It has the same signature but with a callback parameter for the result.



## How to publish



```

yarn version --patch

yarn version --minor

yarn version --major

```



[version-image]: https://img.shields.io/npm/v/tsconfig-paths.svg?style=flat

[version-url]: https://www.npmjs.com/package/tsconfig-paths

[build-image]: https://github.com/dividab/tsconfig-paths/workflows/CI/badge.svg

[build-url]: https://github.com/dividab/tsconfig-paths/actions/workflows/ci.yml?query=branch%3Amaster

[codecov-image]: https://codecov.io/gh/dividab/tsconfig-paths/branch/master/graph/badge.svg

[codecov-url]: https://codecov.io/gh/dividab/tsconfig-paths

[license-image]: https://img.shields.io/github/license/dividab/tsconfig-paths.svg?style=flat

[license-url]: https://opensource.org/licenses/MIT

[prettier-image]: https://img.shields.io/badge/code_style-prettier-ff69b4.svg

[prettier-url]: https://github.com/prettier/prettier