TypeScript

Running wrangler types generates runtime types including the Service and DurableObjectNamespace types, each of which accepts a single type parameter for the WorkerEntrypoint or DurableObject types.

Using higher-order types, we automatically generate client-side stub types (e.g., forcing all methods to be async).

wrangler types also generates types for the env object. You can pass in the path to the config files of the Worker or Durable Object being called so that the generated types include the type parameters for the Service and DurableObjectNamespace types.

For example, if your client Worker had bindings to a Worker in ../sum-worker/ and a Durable Object in ../counter/, you should generate types for the client Worker's env by running:

npm

npx wrangler types -c ./client/wrangler.jsonc -c ../sum-worker/wrangler.jsonc -c ../counter/wrangler.jsonc

yarn

yarn wrangler types -c ./client/wrangler.jsonc -c ../sum-worker/wrangler.jsonc -c ../counter/wrangler.jsonc

pnpm

pnpm wrangler types -c ./client/wrangler.jsonc -c ../sum-worker/wrangler.jsonc -c ../counter/wrangler.jsonc

Note

If your service binding targets a WorkerEntrypoint that is a default export, make sure you set entrypoint: "default" in your Wrangler config when you configure your service binding.

This will produce a worker-configuration.d.ts file that includes:

worker-configuration.d.ts

interface Env {
  SUM_SERVICE: Service<import("../sum-worker/src/index").SumService>;
  COUNTER_OBJECT: DurableObjectNamespace<
    import("../counter/src/index").Counter
  >;
}

Now types for RPC method like the env.SUM_SERVICE.sum method will be exposed to the client Worker.

src/index.ts

export default {
  async fetch(req, env, ctx): Promise<Response> {
    const result = await env.SUM_SERVICE.sum(1, 2);
    return new Response(result.toString());
  },
} satisfies ExportedHandler<Env>;