TypeScript

Turbopack supports TypeScript out of the box. This means you can import .ts files with Turbopack. We support all of TypeScript's feature set.

Thanks to our JSX support, you can also import .tsx files too.

Resolving paths and baseUrl

In TypeScript, you can use the paths property of tsconfig.json to let you import files from custom paths.

{
  "compilerOptions": {
    "baseUrl": "src",
    "paths": {
        "app/*": ["app/*"],
        "config/*": ["app/_config/*"],
        "shared/*": ["app/_shared/*"],
    },
  }
}

This would let you import directly from app/* without needing to do a relative import:

- import { add } from '../../../../../math';
+ import { add } from 'app/math';
 
add();

Turbopack reads the paths and baseUrl in tsconfig.json in order to resolve these paths, just like Next.js does.

This means you only need to configure your absolute paths in one place.

Type Checking

Turbopack does not perform type checks on your application. We use SWC to compile TypeScript code, which also does not perform type checks.

This means that in order to run your type checks, you'll need a sidecar process running tsc --watch. Or, you can rely on your IDE's TypeScript integration.