JavaScript 实现电商限时抢购倒计时功能

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>团购——限时抢</title>

</head>

<body>

<div class="time"> <span id="LeftTime"></span></div>
</div>
<script>
function FreshTime()
{
    var endtime=new Date("2015/11/20,12:20:12");//结束时间
    var nowtime = new Date();//当前时间
    var lefttime=parseInt((endtime.getTime()-nowtime.getTime())/1000); 
    d=parseInt(lefttime/3600/24);
    h=parseInt((lefttime/3600)%24);
    m=parseInt((lefttime/60)%60);
    s=parseInt(lefttime%60);

    document.getElementById("LeftTime").innerHTML="还剩" + d+"天"+h+"小时"+m+"分"+s+"秒";
    if(lefttime<=0){
        document.getElementById("LeftTime").innerHTML="团购已结束";
        clearInterval(sh);
    }
}
    FreshTime();
    var sh;
    sh=setInterval(FreshTime,1000);
</script>
</body>
</html>