"Cannot find module" → How to import other TypeScript files?

[mickaeltr]

Hello,

I am trying to reuse some already existing TypeScript code, in a script.

I have the following config:

➜  ts-node --showConfig
{
  "ts-node": {
    "cwd": "/path",
    "projectSearchDir": "/path",
    "project": "/path/tsconfig.json"
  },
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "allowUnreachableCode": false,
    "allowUnusedLabels": false,
    "baseUrl": "./",
    "declaration": false,
    "emitDecoratorMetadata": true,
    "esModuleInterop": true,
    "exactOptionalPropertyTypes": true,
    "experimentalDecorators": true,
    "forceConsistentCasingInFileNames": true,
    "incremental": true,
    "module": "commonjs",
    "noFallthroughCasesInSwitch": true,
    "noImplicitOverride": true,
    "noImplicitReturns": true,
    "noPropertyAccessFromIndexSignature": true,
    "noUncheckedIndexedAccess": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "outDir": "./.ts-node",
    "paths": {
      "@/*": [
        "src/*"
      ]
    },
    "removeComments": true,
    "skipLibCheck": true,
    "sourceMap": true,
    "strict": true,
    "target": "es2021",
    "inlineSourceMap": false,
    "inlineSources": true,
    "noEmit": false
  }
}

My script runs fine with the following command, when it does not have any import: npx ts-node src/script.ts

However, it starts failing as soon as there is an import like this: import { foo } from "@/bar";

Error is: Cannot find module '@/bar' / code: 'MODULE_NOT_FOUND'

Any help would be appreciated 🙏

[agammann]

Your paths mapping lets TypeScript find src/bar.ts for type checking, but it does not rewrite "@/bar" in the emitted JavaScript. Node then tries to load that name as a package.

For the CommonJS configuration you posted, install the runtime resolver:

npm install --save-dev tsconfig-paths
npx ts-node -r tsconfig-paths/register src/script.ts

Or keep your existing compiler options and add this top-level section to tsconfig.json:

"ts-node": {
  "require": ["tsconfig-paths/register"]
}

I reproduced the MODULE_NOT_FOUND error with your @/* mapping; both forms above loaded src/bar.ts with ts-node 10.9.2, TypeScript 5.9.3 and tsconfig-paths 4.2.0. This recipe is for CommonJS; a native ESM loader needs a different resolution strategy. ts-node's paths documentation describes this setup.

[mickaeltr]

Thank you @agammann I will try that whenever I have a need again for this.