08 Event Emitter

Review

  1. 2024-08-13 07:51

[!Summary] EventEmitter 是发布订阅模式在 Node.js 中的具体实现，它通过事件、监听器、发布和订阅等机制，实现了对象之间松耦合的通信。

一、Introduction #

import EventEmitter from 'node:events';

const eventEmitter = new EventEmitter();

const handler = (num: number) => {
  console.log('started', num);
}

eventEmitter.on('start', handler);

eventEmitter.emit('start', 111);

eventEmitter.off('start', handler);

eventEmitter.emit('start', 111);

eventEmitter.removeAllListeners('start'); // 取消所有 start 事件监听
  • emit is used to trigger an event
  • on is used to add a callback function that’s going to be executed when the event is triggered
  • once(): add a one-time listener
  • removeListener() / off(): remove an event listener from an event
  • removeAllListeners(): remove all listeners for an event

Reference #