Vue implement a communication method of EventBus

  There are many ways vue communication, there are more and more used in the project of pros、vuex、$emit/$onthese three, as well as provide/inject(for higher-order components), $attrs和$listeners(suitable for high-order components) and $parent/$child/ref、eventBusso on three ways. Many times we are only using the api, and understand the principles and achieve, but I think not in the same level with the time to understand the principles and achieve a just call api developers. So here it is like the cross-component communication eventBusTheory of Communication to show you what. This is also the chiefs of the things he learned and on this record (reproduced) it.

    class EventBus{
        constructor(){
            this.event=Object.create(null);
        };
        //注册事件
        on(name,fn){
            if(!this.event[name]){
                //一个事件可能有多个监听者
                this.event[name]=[];
            };
            this.event[name].push(fn);
        };
        //触发事件
        emit(name,...args){
            //给回调函数传参
            this.event[name]&&this.event[name].forEach(fn => {
                fn(...args)
            });
        };
        //只被触发一次的事件
        once(name,fn){
            //在这里同时完成了对该事件的注册、对该事件的触发，并在最后取消该事件。
            const cb=(...args)=>{
                //触发
                fn(...args);
                //取消
                this.off(name,fn);
            };
            //监听
            this.on(name,cb);
        };
        //取消事件
        off(name,offcb){
            if(this.event[name]){
                let index=this.event[name].findIndex((fn)=>{
                    return offcb===fn;
                })
                this.event[name].splice(index,1);
                if(!this.event[name].length){
                    delete this.event[name];
                }
            }
        }
    }
复制代码

The above code using a publish-subscribe model.

Reference links:
1, the interviewer Series (2): Event Bus achieve
2, a qualified mid-level front-end engineers must master the skills of 28 JavaScript