JavaScript实现发布与订阅

1、代码

class EventBus {
  constructor(){
    this.events = {};
  }
  on(event,handler){
   if(!this.events[event]){
     this.events[event] = [];
   }
    this.events[event].push(handler);
  }
  emit(event,data){
    if (this.events[event]){
      this.events[event].forEach((handler)=>{
        handler(data);
      })
    }
  }
  off(event,handler){
    if (this.events[event]) {
      this.events[event] = this.events[event].filter(h=>h !== handler)
    }
  }
  remove(event){
    delete this.events[event]
  }
}
export {
  EventBus
} 

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2、使用方法

　　

const $bus = new EventBus();
//订阅

$bus.on("greet", func)

  //发布

 $bus.emit("greet", "word");

　//取消订阅

  $bus.off("greet"，func);

 //删除订阅

  $bus.remove("greet");

 

　function func(arg){

　　console.log(arg)

　}

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