tsconfig-paths

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Use this to load modules whose location is specified in the paths section of tsconfig.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 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 and convert node's module loading calls into to physcial file paths that node can load.

How to install

``
yarn add --dev tsconfig-paths
`

or

`
npm install --save-dev tsconfig-paths
`

How to use

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node -r tsconfig-paths/register main.js

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

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

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For webpack please use the tsconfig-paths-webpack-plugin.

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As of Mocha >= 4.0.0 the --compiler was deprecated. 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"
`

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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.

Bootstraping 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.

`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"
`

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_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
- loadConfig
- createMatchPath / createMatchPathAsync
- matchFromAbsolutePaths / matchFromAbsolutePathsAsync

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`typescript
export interface ExplicitParams {
baseUrl: string;
paths: { [key: string]: Array };
mainFields?: Array;
addMatchAll?: boolean;
}

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

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`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. It will start searching from the specified cwd directory.

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`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.
@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[] = ["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 signare specified by the type MatchPath above.

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`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 existance 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.
* @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[] = ["main"]
): string | undefined {
`

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

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

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

[version-image]: https://img.shields.io/npm/v/tsconfig-paths.svg?style=flat
[version-url]: https://www.npmjs.com/package/tsconfig-paths
[travis-image]: https://travis-ci.com/dividab/tsconfig-paths.svg?branch=master&style=flat
[travis-url]: https://travis-ci.com/dividab/tsconfig-paths
[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