手写发布订阅

发布订阅是一种常见的设计模式，也成为观察者模式。它基于事件处理机制，允许多个观察者订阅某个事件，当时间被触发时，所有订阅该事件的观察者都会收到通知。

实现发布订阅的代码：

const PubSub = () => {
    let subscribers = {};

    //订阅事件
    const subscribe = (eventName, callback) => {
        if (!subscribers[eventName]) {
            subscribers[eventName] = [];
        }
        subscribers[eventName].push(callback);
    }

    //发布事件
    const publish = (eventName, ...args) => {
        if (subscribers[eventName]) {
            subscribers[eventName].forEach(callback => {
                callback(...args);
            })
        }
    }

    //取消订阅
    const unsubscribe = (eventName, callback) => {
        if (subscribers[eventName]) {
            subscribers[eventName] = subscribers[eventName].filter(cb => cb != callback);
        }
    }

    return { subscribe, publish, unsubscribe };
}

//定义新的订阅发布
const pubSub1 = PubSub();

//定义订阅者怎样处理发布的信息
const click1 = (a, b) => {
    console.log(a , b, 'click1')
}
const click2 = (a, b) => {
    console.log(a , b, 'click2')
}
//将订阅者推到订阅者列表中
pubSub1.subscribe('click', click1);
pubSub1.subscribe('click', click2);
//发布click事件
pubSub1.publish('click', 1, 2);
//click1取消订阅click事件
pubSub1.unsubscribe('click', click1);
//发布click事件
pubSub1.publish('click', 1, 2);