JavaScript记时秒杀功能

var dt = new Date(), hour = dt.getHours(),date = dt.getDay();
var end = new Date(dt.getYear(),dt,getMonth(),date,12) //活动结束时间
var diff = end - dt;
var timer = setInterval(function(){
    if(dt > 0 && hour > 10){ //hour > 10 活动开始时间
       //do something
    }else{
      //do something
      clearInterval(timer);
    }
    diff -= 1000; //timer 1sec
},1000)