pub/sub原理

实现一个简单地pubsub事件触发,传递机制:

 var events = {
                events:{},
                on:function(eventName,fn){
                    this.events[eventName] = this.events[eventName]||[];
                    this.events[eventName].push(fn);
                },
                off:function(eventName,fn){
                    if(this.events[eventName]){
                        for(var i=0;i<this.events[eventName].length;i++){
                            if(this.events[eventName][i]===fn){
                                this.events[eventName].splice(i,1);
                                break;
                            }
                        }
                    }
                },
                emit:function(eventName,data){
                    if(this.events[eventName]){
                        this.events[eventName].forEach((fn)=>fn(data));
                    }
                }

            }