TypeScript Compiler Path Prefixer

Fix VS Code terminal links when using lerna by prefixing file paths in tsc output.

Motivation

When building TypeScript packages in a monorepository using lerna, file paths in tsc output are relative to the package folder, not the root folder of the monorepository. This breaks VS Code's terminal hyperlink functionality.

This utility prefixes file paths in tsc output so they are relative to the root of the monorepository and recognized by VS Code.

Install

yarn add --dev tsc-path-prefix

Shell Usage

After invoking tsc in a package with lerna --prefix, pipe it through tsc-path-prefix. The lerna project configuration will be inspected and the tsc output path prefixed with the package path.

yarn lerna build:watch --parallel --prefix | tsc-path-prefix

You can use tsc-path-prefix independently of lerna by supplying a prefix as an argument on invocation:

yarn build:watch --parallel | tsc-path-prefix 'libraries/my-library'

Gotchas

When piping to tsc-path-prefix from lerna the parent shell will have its process.stdout.isTTY set to false causing the underlying chalk library used by lerna not to output colours. Set the FORCE_COLOUR environment variable to force coloured output when piping to tsc-path-prefix.

FORCE_COLOR=1 yarn build:watch --parallel --prefix | tsc-path-prefix

Errors reported by tsc are sent to stderr and not piped downstream via stdout. To redirect tsc stderr to stdout you must invoke lerna with either --paralell or --stream, or use tsc 2>&1 | tsc-path-prefix.

Monorepository Usage

Use tsc-path-prefix in your root package.json scripts:

{
  "devDependencies": {
    "@stemn/tsc-path-prefix": "^0.0.1",
    "lerna": "^3.4.3"
  },
  "lerna": {
    "packages": [
      "libraries/*"
    ],
    "version": "3.4.3"
  },
  "name": "monorepo",
  "scripts": {
    "build:watch": "yarn lerna run build:watch --parallel | tsc-path-prefix"
  }
}

libraries/my-library/package.json

{
  "name": "@monorepo/my-library",
  "devDependencies": {
    "typescript": "^3.1.3"
  },
  "scripts": {
    "build:watch": "tsc --watch"
  }
}

Example

Before

Lerna output will contain tsc paths relative to the root folder of the package.

@monorepo/my-library: [10:08:07 AM] Starting compilation in watch mode...
@monorepo/my-library: src/index.ts:9:6 - error TS2339: Property 'badProperty' does not exist on type 'ITestInterface'.
@monorepo/my-library: 9 test.badProperty = 'error';
@monorepo/my-library:        ~~~~~~~~~~~
@monorepo/my-library: [10:08:12 AM] Found 1 error. Watching for file changes.

After

Lerna output will contain tsc paths relative to the root folder of the monorepository.

@monorepo/my-library: [10:08:07 AM] Starting compilation in watch mode...
@monorepo/my-library: libraries/my-library/src/index.ts:9:6 - error TS2339: Property 'badProperty' does not exist on type 'ITestInterface'.
@monorepo/my-library: 9 test.badProperty = 'error';
@monorepo/my-library:        ~~~~~~~~~~~
@monorepo/my-library: [10:08:12 AM] Found 1 error. Watching for file changes.

Diff

$ tsc

-@monorepo/my-library: src/index.ts:9:6
+@monorepo/my-library: libraries/my-library/src/index.ts:9:6

Testing

git clone [email protected]:stemn/tsc-path-prefix.git
cd tsc-path-prefix
yarn install
yarn test