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HTML

              
                <button id="demo">点击事件</button>

              
            
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CSS

              
                
              
            
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JS

              
                const button = document.getElementById('demo');
button.addEventListener('click',function(){
  alert(1)
})
button.addEventListener('click',function(){
  alert(2)
})
// button.click()
let Event= {
  clientList:[],
  // 缓存事件列表 思路 需要为每个事件记录已经发送的key 如果新增事件的是 发现之前有缓存事件没触发 那么需要执行之前的事件?
  cacheBroadList:[],
  listen :function(key,fn){
    if(typeof(fn) === 'function'){
      if(!(key in this.clientList)){
//         之前没有这个对象 那么需要补发所有的事件
        this.clientList[key] = []
      } 
      this.clientList[key].push(fn)
      if(this.cacheBroadList.length > 0){
          for(let i = 0 ,len = this.cacheBroadList.length;i < len ;i++){
           
            this.broad(this.cacheBroadList[i],key)
          }
        }
    } else{
      throw Error("非函数类型")
    }
    
  },
  broad:function(msg,watcher){
//     缓存下来所有的事件
    this.cacheBroadList.push('oldMsg' + msg)
    if(!watcher){
        for(let p in this.clientList){
        if(this.clientList[p].length === 0 ) return false;
      for(let i = 0,len = this.clientList[p].length ;i<len;i++){
        this.clientList[p][i] && this.clientList[p][i](msg)
      }
    }
    }
    else{
      for(let i = 0,len = this.clientList[watcher].length ;i<len;i++){
        this.clientList[watcher][i] && this.clientList[watcher][i](msg)
      }
     
    }
  
  
  }
}
Event.remove = function(key,fn){
  var fns = this.clientList[key];
  if(!fns){return false ;}
  if(!fn && fns){
     fns.length = 0
  }
  for(let i = fns.length - 1;i>= 0 ; i--){
    let _fn = fns[i];
  	if(_fn === fn){
      fns.splice(i, 1);
    }
  }
}

Event.broad('有40万的房子销售了')
Event.listen('xiaozhang',function(msg){
  console.log('xiaozhang:' + msg)
})
Event.broad('有120万的房子销售了')

Event.listen('xiaowang',function(msg){
  console.log('xiaowang:' + msg)
})

// Event.remove('xiaowang')
Event.broad('有130万的房子销售了')


const installEvent = (oriObj) => {
  for(let p in Event){
    oriObj[p] = Event[p];
  }
}
let salesOffices = {
  name:'销售办公室',
  sales:'小航',
}
installEvent(salesOffices)
// salesOffices.broad('有房子销售了')
              
            
!
999px

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