JS倒计时-优快云博客

<html>  
  <head>  
      <meta charset="UTF-8">  
      <title>js简单时分秒倒计时</title>  
 </head>  
 <body onload="countTime()" >  
     <div>  
         <span id="_d">00</span>  
         <span id="_h">00</span>  
         <span id="_m">00</span>  
         <span id="_s">00</span>  
     </div>  
</body>  
</html>

<script type="text/javascript">  
    function countTime() {  
        //获取当前时间  
        var date = new Date();  
        var now = date.getTime();  
       //设置截止时间  
       var str="2021/1/1 00:00:00";
       var endDate = new Date(str); 
       var end = endDate.getTime();  
       
       //时间差  
       var leftTime = end-now; 
       //定义变量 d,h,m,s保存倒计时的时间  
       var d,h,m,s;  
       if (leftTime>=0) {  
           d = Math.floor(leftTime/1000/60/60/24);  
           h = Math.floor(leftTime/1000/60/60%24);  
           m = Math.floor(leftTime/1000/60%60);  
           s = Math.floor(leftTime/1000%60);                     
       }  
       //将倒计时赋值到div中  
       document.getElementById("_d").innerHTML = d+"天";  
       document.getElementById("_h").innerHTML = h+"时";  
       document.getElementById("_m").innerHTML = m+"分";  
       document.getElementById("_s").innerHTML = s+"秒";  
       //递归每秒调用countTime方法，显示动态时间效果  
       setTimeout(countTime,1000);  

   }  
</script>