SOURCE

// 简单的订阅/发布模式
class Event{
    eventArr= []

    constructor() {

    }

    on(name, fn) {
        if (!this.eventArr[name]) {
            this.eventArr.push(fn);
        }
    }

    emit() {
        console.log('发布啦....');
        this.eventArr.forEach(function(fn){
            fn();
        })
    }
}

const obj= new Event();
obj.on('fn1', function(){
    console.log('fn1....')
})
obj.on('fn2', function(){
    console.log('fn2....')
})
obj.on('fn3', function(){
    console.log('fn3....')
})
obj.emit();