发布-订阅模式

红绿灯

class Light{
    constructor() {
      this.drivers = [];
    }

    // 只用缓存订阅者的接收方法，而不需要他的个人信息
    regist(fn){
        this.drivers.push(fn);
    }

    sendMsg() {
        this.drivers.forEach(fn => {
            // driver.recieveMsg(msg);
            // fn.apply(this, msg);
            fn.apply(this, arguments);
        });
    }
}

class Driver{
    constructor(name) {
        this.name = name;
    }
    recieveMsg(msg) {
        // 如果用apply的话，订阅者如果知道发布者保存所有订阅者的变量名drivers，那么他就可以访问到别的订阅者的订阅函函数
        console.log(' recieve ' + this.drivers);
    }
}

const light = new Light();
const driver1 = new Driver('driver1');
const driver2 = new Driver('driver2');
const driver3 = new Driver('driver3');

light.regist(driver1.recieveMsg);
light.regist(driver2.recieveMsg);
light.regist(driver3.recieveMsg);

light.sendMsg('red!');

只订阅自己想订阅的内容

class Light{
    constructor() {
      this.drivers = [];
    //   {
    //       red: [fn1. fn2, fn3],
    //       ...
    //   }
    }

    regist(key, fn){
        // 订阅新关键字
        if (!this.drivers[key]){
            this.drivers[key] = [];          
        }             
        this.drivers[key].push(fn);
    }

    sendMsg(key) {
        if(!this.drivers[key])return false;
        this.drivers[key].forEach(fn => {
            fn.apply(this, arguments);
        });
    }
}

class Driver{
    constructor(name) {
        this.name = name;
    }
    recieveMsg(msg) {
        console.log(' recieve ' + msg);
    }
}

const light = new Light();
const driver1 = new Driver('driver1');
const driver2 = new Driver('driver2');
const driver3 = new Driver('driver3');

light.regist('red', driver1.recieveMsg);
light.regist('green', driver2.recieveMsg);
light.regist('yellow', driver3.recieveMsg);

console.log(light);

light.sendMsg('red');