javascript实现倒计时程序

最近在网上看到一道这样的面试题：

题： 网页中实现一个计算当年还剩多少时间的倒数计时程序，要求网页上实时动态显示“××年还剩××天××时××分××秒”？

我实现了，发现挺有意思，下面把我的代码贴出来

<!doctype html>
<html  lang="en">
<head>
<meta charset="utf-8">
<script type="text/javascript">
    function dayBetween(){
        var today = new Date();
        var enday = new Date(2016,11,31,0,0,0,0);  //或 new Date("2016/12/31 0:0:0");
        var between = enday-today;
       // console.log("between"+between+"
");
        var sec = Math.floor(between/1000);
        var day = Math.floor((Math.floor((Math.floor(sec/60))/60))/24); 
        var hours = (Math.floor((Math.floor(sec/60))/60))%24;
        var minutes = (Math.floor(sec/60))%60 ;
        var seconds =  sec%60;
       // console.log("result:"+day+"天"+hours+"时"+minutes+"分"+seconds+"秒");
       var t = document.getElementById("time");
       t.innerHTML = "离2016年12月31日0点还剩："+"<b>"+day+"天"+hours+"时"+minutes+"分"+seconds+"秒"+"</b>";
    }
    window.onload = function(){
      setInterval(dayBetween,1000);
    };
</script>
</head>
<body>
<p id="time"></p>
</body>
</html>