Surprising Discovery: TypeScript - node_modules Found in Unusual Directory

Is there a way to make TypeScript imports function properly even if the node_modules directory is not directly in the tree?

How can I prevent TypeScript from throwing errors when importing something like rxjs from external/node_modules.

For Example:

Directory Structure:

|-- external
|  `-- package.json
|-- index.ts
`-- tsconfig.json

Contents of tsconfig.json:

{
    "compilerOptions": {
        "module": "amd",
        "target": "es5",
        "sourceMap": true,
        "removeComments": true,
        "allowJs": false,
        "pretty": true,
        "experimentalDecorators": true,
        "moduleResolution": "node",
        "emitDecoratorMetadata": true,
        "lib": [ "es2015", "dom" ]
    }
}

Contents of external/package.json:

{
    "name": "external",
    "version": "1.0.0",
    "main": "index.js",
    "license": "MIT",
    "dependencies": {
        "rxjs": "^5.0.3"
    }
}

Contents of index.ts:

import { Observable } from 'rxjs/Rx';
Observable

Navigate to the external directory:

Run yarn install command:

yarn add v0.18.1
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
[4/4] 📃  Building fresh packages...
success Saved lockfile.
success Saved 2 new dependencies.
├─ [email protected]
└─ [email protected]
✨  Done in 1.39s.

Check TypeScript version:

Version 2.1.4

Compile TypeScript:

1 import { Observable } from 'rxjs/Rx';
                             ~~~~~~~~~

../index.ts(1,28): error TS2307: Cannot find module 'rxjs/Rx'.
typescript

Answer №1

To implement path mapping in tsconfig.json, refer to the official documentation:

  "compilerOptions": {
    ....
    "baseUrl": ".", // Make sure to include this when using "paths".
    "paths": {
      "rxjs/Rx": ["external/node_modules/rxjs/Rx"]
    }
  }

Remember to define a paths mapping for each module imported from non-standard locations.

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