倒计时

    html
    <div class="countDown">
        <span id="countDown-day">00</span> 天
        <span id="countDown-hour">00</span> 时
        <span id="countDown-minute">00</span> 分
        <span id="countDown-second">00</span> 秒
    </div>

    js代码
    
    var month=new Date().getMonth()+1;
    var year=new Date().getFullYear();
    var date = new Date(year,month,0);
    var endTime = year + '/' + month + '/' + new Date(date).getDate() + ' 23:59:59';
    var _ordertimer = setInterval(function(){
        countDownFun(endTime)
    }, 1000);
	function countDownFun(val){ 
	  var leftTime = new Date(val) - new Date(); //计算剩余的毫秒数 
	  var days = parseInt(leftTime / 1000 / 60 / 60 / 24 , 10); //计算剩余的天数 
	  var hours = parseInt(leftTime / 1000 / 60 / 60 % 24 , 10); //计算剩余的小时 
	  var minutes = parseInt(leftTime / 1000 / 60 % 60, 10);//计算剩余的分钟 
	  var seconds = parseInt(leftTime / 1000 % 60, 10);//计算剩余的秒数 
	  days = checkTime(days); 
	  hours = checkTime(hours); 
	  minutes = checkTime(minutes); 
	  seconds = checkTime(seconds);
      if (parseInt(leftTime/1000) < 0) {
        clearInterval(_ordertimer)
      }else{
        $("#countDown-day").html(days)
        $("#countDown-hour").html(hours)
        $("#countDown-minute").html(minutes)
        $("#countDown-second").html(seconds)
      }
	}
	function checkTime(i){ //将0-9的数字前面加上0，例1变为01 
	  if(i<10) { 
	    i = "0" + i; 
	  }
	  return i; 
	}