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What does the events.once() helper do and how does it bridge EventEmitter and async/await?

Q: What does the events.once() helper do and how does it bridge EventEmitter and async/await?

**TL;DR.** events.once(emitter, name) returns a **Promise that resolves with the next emission** of that event (and **rejects** if the emitter fires 'error' first). It lets you await a one-shot event — like a server 'listening' or a stream 'end' — instead of wiring up .on() callbacks. emitter emit('ready') once() await

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Awaiting a single emitted event as a promise.

nodejseventsasynceventemitter

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Await a server starting

import { once } from 'node:events';
import { createServer } from 'node:http';

const server = createServer().listen(3000);
await once(server, 'listening');     // resolves when ready
console.log('server is up');

// With a deadline:
await once(server, 'listening', { signal: AbortSignal.timeout(5000) });

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