nodeaa.js

class SimplePubSub {
  constructor() {
    this.events = {};
  }

  subscribe(event, listener) {
    if (!this.events[event]) {
      this.events[event] = [];
    }
    this.events[event].push(listener);
  }

  unsubscribe(event, listener) {
    if (!this.events[event]) return;
    this.events[event] = this.events[event].filter((l) => l !== listener);
  }

  publish(event, data) {
    if (!this.events[event]) return;
    this.events[event].forEach((listener) => listener(data));
  }
}

// 创建 PubSub 实例
const pubSub = new SimplePubSub();

// 定义订阅者
const subscriber1 = (data) => {
  console.log(`Subscriber 1 received: ${data}`);
};

const subscriber2 = (data) => {
  console.log(`Subscriber 2 received: ${data}`);
};

// 订阅事件
pubSub.subscribe("event1", subscriber1);
pubSub.subscribe("event1", subscriber2);

// 发布事件
pubSub.publish("event1", "Hello, World!");

// 取消订阅
pubSub.unsubscribe("event1", subscriber1);

// 发布事件
pubSub.publish("event1", "Hello again!");

// 输出应该是如下的样式
/*
Subscriber 1 received: Hello, World!
Subscriber 2 received: Hello, World!
Subscriber 2 received: Hello again!
*/