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Real-time Events ​

Problem ​

You need to consume notifications from an SSE endpoint and stop the connection when the view no longer needs updates.

Solution ​

Iterate events() and use break when the current consumer is finished; Courier aborts the connection immediately.

ts
import { createCourier } from '@vielzeug/courier';

type Notification = { roomId: string; text: string; userId: string };

const courier = createCourier({ baseUrl: 'https://api.example.com' });

for await (const event of courier.events<Notification>('/events', {
  query: { roomId: 'general' },
})) {
  if (event.event !== 'message') continue;
  console.log(`[${event.data.roomId}] ${event.data.userId}: ${event.data.text}`);
  break; // Closes the active SSE request immediately.
}

Pitfalls ​

  • Courier does not reconnect automatically. Recreate the iterator only when reconnecting is safe.
  • A stream started after courier.dispose() rejects with CourierDisposedError.
  • Handle CourierAbortError separately when cancellation is normal application control flow.