js倒计时

    
    window.onload = clock;
    function clock() {
 //获取结束的时间戳
 var timestamp = $("#shijiancuo").attr("title");
 //根据时间戳生成的时间对象
 var stop = new Date(timestamp * 1000);
 //获取当前时间
 var today = new Date();
 //剩余时间
 var shenyu = stop.getTime() - today.getTime(),//倒计时毫秒数
     shengyuD = parseInt(shenyu / (60 * 60 * 24 * 1000)),//转换为天
     D = parseInt(shenyu) - parseInt(shengyuD * 60 * 60 * 24 * 1000),
     shengyuH = parseInt(D / (60 * 60 * 1000)),//转换为小时
     H = D - shengyuH * 60 * 60 * 1000,
     shengyuM = parseInt(H / (60 * 1000)),//转换为分钟
     M = H - shengyuM * 60 * 1000;

 shengyuS = parseInt((shenyu - shengyuD * 60 * 60 * 24 * 1000 - shengyuH * 60 * 60 * 1000 - shengyuM * 60 * 1000) / 1000);//转换为秒
 //小于 10 的时候在前面加 0
 if (shengyuS < 10) {
     shengyuS = "0" + shengyuS
 } else {
     shengyuS
 }
 if (shengyuH < 10) {
     shengyuH = "0" + shengyuH
 } else {
     shengyuH
 }
 if (shengyuM < 10) {
     shengyuM = "0" + shengyuM
 } else {
     shengyuM
 }
 if (shengyuD < 10) {
     shengyuD = "0" + shengyuD
 } else {
     shengyuD
 }
 document.getElementById("time1").innerHTML = shengyuD;
 document.getElementById("time2").innerHTML = shengyuH;
 document.getElementById("time3").innerHTML = shengyuM;
 document.getElementById("time4").innerHTML = shengyuS;
 setTimeout("clock()", 500);
    }