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Request scoping ​

Problem ​

Implement request scoping in a production-friendly way with @vielzeug/eventit while keeping setup and cleanup explicit.

Runnable Example ​

The snippet below is copy-paste runnable in a TypeScript project with @vielzeug/eventit installed.

Scope a bus to a single request and dispose it on cleanup:

ts
async function handleRequest(req: Request): Promise<Response> {
  using requestBus = createBus<RequestEvents>();

  requestBus.on('data:loaded', (data) => cache.set(req.url, data));

  await processRequest(req, requestBus);

  return buildResponse();
} // requestBus.dispose() called automatically

Expected Output ​

  • The example runs without type errors in a standard TypeScript setup.
  • The main flow produces the behavior described in the recipe title.

Common Pitfalls ​

  • Forgetting cleanup/dispose calls can leak listeners or stale state.
  • Skipping explicit typing can hide integration issues until runtime.
  • Not handling error branches makes examples harder to adapt safely.