Cloudflare Docs
Edit this page
Give us feedback
Set theme to dark (⇧+D)


An EventEmitter is an object that emits named events that cause listeners to be called.

import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.on('hello', (...args) => {
emitter.emit('hello', 1, 2, 3);

The implementation in the Workers runtime fully supports the entire Node.js EventEmitter API. This includes the captureRejections option that allows improved handling of async functions as event handlers:

const emitter = new EventEmitter({ captureRejections: true });
emitter.on('hello', async (...args) => {
throw new Error('boom');
emitter.on('error', (err) => {
// the async promise rejection is emitted here!

Refer to the Node.js documentation for EventEmitter for more information.