发布订阅模式

[nmsn]

如题

[nmsn]

// 通用发布订阅模式
class EventEmitter {
  // 订阅者列表
  subscriber = {};
​
  // 订阅
  subscribe(key, fn) {
    if (!Array.isArray(this.subscriber[key])) {
      this.subscriber[key] = [];
    }
    this.subscriber[key].push(fn);
  }
​
  // 取消单个订阅
  unsubscribe(key, fn) {
    const subscribers = this.subscriber[key] || [];
    this.subscriber[key] = subscribers.filter((_fn) => _fn !== fn);
  }
​
  // 取消所有订阅
  unsubscribeAll(key) {
    this.subscriber[key] = [];
  }
​
  // 发布
  publish(key, ...args) {
    const subscribers = this.subscriber[key] || [];
​
    if (subscribers.length === 0) {
      console.log("has't subscriber");
    }
​
    subscribers.forEach((subscriber) => {
      subscriber.apply(this, args);
    });
  }
}
​
// 创建发布订阅信道中介
const e = new EventEmitter();
​
// 发布者
const publisher = {
  article1: 'article1',
  article2: 'article2',
};
​
// 订阅者
const subscriber1 = (article) => {
  console.log(`fans1 receive ${article}`);
};
const subscriber2 = (article) => {
  console.log(`fans2 receive ${article}`);
};
​
// 订阅操作
e.subscribe('event1', subscriber1);
e.subscribe('event1', subscriber2);
​
// 发布操作
e.publish('event1', publisher.article1);
// fans1 receive article1
// fans2 receive article1
​
// 多事件发布订阅
e.subscribe('event2', subscriber1);
e.publish('event2', publisher.article1);
// fans1 receive article1
​
// 取消单个订阅
e.unsubscribe('event1', subscriber1);
e.publish('event1', publisher.article2);
// fans2 receive article2
​
// 取消所有订阅
e.unsubscribeAll('event1');
e.publish('event1');
// has't subscriber