js 设置时间戳,进行倒计时。比如距离活动结束时间等等

<html>  
<head>  
    <meta charset="UTF-8">  
    <title>js简单时分秒倒计时</title>  
    <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="2017/5/17 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+"";  
            document.getElementById("_h").innerHTML = h+"";  
            document.getElementById("_m").innerHTML = m+"";  
            document.getElementById("_s").innerHTML = s+"";  
            //递归每秒调用countTime方法,显示动态时间效果  
            setTimeout(countTime,1000);  
  
        }  
    </script>  
</head >  
<body οnlοad="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>
原文链接:https://blog.csdn.net/sinat_31177681/article/details/83352220
原文地址:https://www.cnblogs.com/hb88/p/12152634.html