vue 向上通知、向下广播（子传父，父传子）

1.向上通知

Vue.prototype.$dispatch = (eventName, value) => {

    let parent = this.$parent

    while(parent){

        parent.$emit(eventName, value)

        parent = parent.$parent

    }

}

2.向下广播

Vue.prototype.$boardcast = (eventName, value) => {

    const boardcast = (children) => {

        children.foreach(child =>{

            child.$emit(eventName, value)

            if(child.$children) {

                boardcast (child.$children)

            }

        })

    }

    boardcast(this.$children)

}