发布订阅模式（Publish-Subscribe Pattern），也称为观察者模式，是一种常用的设计模式，用于对象之间的消息传递。在这个模式中，订阅者（Observer）注册到发布者（Subject），当发布者状态发生变化时，通知所有订阅者。
下面是一个 JavaScript 实现的发布订阅模式：
class PubSub {constructor() {this.subscribers = {};}// 订阅事件subscribe(event, callback) {if (!this.subscribers[event]) {this.subscribers[event] = [];}this.subscribers[event].push(callback);}// 取消订阅unsubscribe(event, callback) {if (!this.subscribers[event]) return;this.subscribers[event] = this.subscribers[event].filter(subscriber => subscriber !== callback);}// 发布事件publish(event, data) {if (!this.subscribers[event]) return;this.subscribers[event].forEach(callback => callback(data));}
}// 使用示例
const pubSub = new PubSub();function subscriber1(data) {console.log(`Subscriber 1 received data: ${data}`);
}function subscriber2(data) {console.log(`Subscriber 2 received data: ${data}`);
}// 订阅事件
pubSub.subscribe('event1', subscriber1);
pubSub.subscribe('event1', subscriber2);// 发布事件
pubSub.publish('event1', 'Hello World!');
// 输出:
// Subscriber 1 received data: Hello World!
// Subscriber 2 received data: Hello World!// 取消订阅
pubSub.unsubscribe('event1', subscriber2);// 发布事件
pubSub.publish('event1', 'Hello again!');
// 输出:
// Subscriber 1 received data: Hello again!