比较全的JavaScript倒计时脚本[xyytit]

需要做一个功能，给特定的活动或者商品添加一个倒计时提示，在网上找了好些方法，总结了比较好的一些方法，以备后用：

1. 比较长时间的倒计时（如：距离2014年还有0年, 0月, 30天, 9小时, 41分, 17秒）

 <script type="text/javascript">
 startclock();
 var timerID = null;
 var timerRunning = false;
 function showtime() {
     Today = new Date();
     var year = Today.getFullYear();
     document.getElementById("next_yeat").innerHTML = year + 1;
     var NowHour = Today.getHours();
     var NowMinute = Today.getMinutes();
     var NowMonth = Today.getMonth();
     var NowDate = Today.getDate();
     var NowYear = Today.getYear();
     var NowSecond = Today.getSeconds();
     if (NowYear <2000)
     NowYear=1900+NowYear;
     Today = null;
     Hourleft = 23 - NowHour
     Minuteleft = 59 - NowMinute
     Secondleft = 59 - NowSecond
     Yearleft = year - NowYear
     Monthleft = 12 - NowMonth - 1
     Dateleft = 31 - NowDate
     if (Secondleft<0)
     {
         Secondleft=60+Secondleft;
         Minuteleft=Minuteleft-1;
     }
     if (Minuteleft<0)
     {
         Minuteleft=60+Minuteleft;
         Hourleft=Hourleft-1;
     }
     if (Hourleft<0)
     {
         Hourleft=24+Hourleft;
         Dateleft=Dateleft-1;
     }
     if (Dateleft<0)
     {
         Dateleft=31+Dateleft;
         Monthleft=Monthleft-1;
     }
     if (Monthleft<0)
     {
         Monthleft=12+Monthleft;
         Yearleft=Yearleft-1;
     }
     Temp=Yearleft+'年, '+Monthleft+'月, '+Dateleft+'天, '+Hourleft+'小时, '+Minuteleft+'分, '+Secondleft+'秒';
     document.form1.left.value=Temp;
     timerID = setTimeout("showtime()",1000);
     timerRunning = true;
 }
 var timerID = null;
 var timerRunning = false;
 function stopclock () {
     if(timerRunning)
     clearTimeout(timerID);
     timerRunning = false;
 }
 function startclock () {
     stopclock();
     showtime();
 }
 // -->
 </script>   

2. 小时倒计时（如：距离结束还有 42 分 5 秒）

 <script type="text/javascript">
 <!--
 //一个小时，按秒计算，可以自己调整时间
 var maxtime = 60*60
 function CountDown()
 {
     if(maxtime>=0)
     {
         minutes = Math.floor(maxtime/60);
         seconds = Math.floor(maxtime%60);
         msg = "距离结束还有 "+minutes+" 分 "+seconds+" 秒";
         document.all["timer"].innerHTML=msg;
         if(maxtime == 5*60) alert('注意，还有5分钟!');
         --maxtime;
     }
     else
     {
         clearInterval(timer);
         alert("时间到，结束!");
     }
 }
 timer = setInterval("CountDown()",1000);
 //-->
 </script>

3. 最简倒计时（如：现在离 2014 还有: 30 天）

 <script Language="JavaScript">
 <!-- Begin
 　　var timedate= new Date("January 14,2012");
 　　var times="2012";
 　　var now = new Date();
 　　var date = timedate.getTime() - now.getTime();
 　　var time = Math.floor(date / (1000 * 60 * 60 * 24));
 　　if (time >= 0) ;
 document.write("<p>现在离 "+times+" 还有: <b>"+time +"</b> 天</p>");
 // End -->
 </script>   

4. 秒表功能（如：00:01:11:00）

 <script type="text/javascript">
 var normalelapse = 100;
 var nextelapse = normalelapse;
 var counter;
 var startTime;
 var start = clock.innerText;
 var finish = "00:00:00:00";
 var timer = null;
 // 开始运行
 function run() {
     startB.disabled = true;
     endB.disabled = false;
     counter = 0;
     // 初始化开始时间
     startTime = new Date().valueOf();   

     // nextelapse是定时时间, 初始时为100毫秒
     // 注意setInterval函数: 时间逝去nextelapse(毫秒)后, onTimer才开始执行
     timer = window.setInterval("onTimer()", nextelapse);
 }
 // 停止运行
 function stop() {
     startB.disabled = false;
     endB.disabled = true;
     window.clearTimeout(timer);
 }
 window.onload = function() {
     endB.disabled = true;
 }
 // 倒计时函数
 function onTimer()
 {
     if (start == finish)
     {
         window.clearInterval(timer);
         alert("time is up!");
         return;
     }
     var hms = new String(start).split(":");
     var ms = new Number(hms[3]);
     var s = new Number(hms[2]);
     var m = new Number(hms[1]);
     var h = new Number(hms[0]);
     ms -= 10;
     if (ms < 0)
     {
         ms = 90;
         s -= 1;
         if (s < 0)
         {
             s = 59;
             m -= 1;
         }
         if (m < 0)
         {
             m = 59;
             h -= 1;
         }
     }
     var ms = ms < 10 ? ("0" + ms) : ms;
     var ss = s < 10 ? ("0" + s) : s;
     var sm = m < 10 ? ("0" + m) : m;
     var sh = h < 10 ? ("0" + h) : h;
     start = sh + ":" + sm + ":" + ss + ":" + ms;
     clock.innerText = start;   

     // 清除上一次的定时器
     window.clearInterval(timer);
     // 自校验系统时间得到时间差, 并由此得到下次所启动的新定时器的时间nextelapse
     counter++;
     var counterSecs = counter * 100;
     var elapseSecs = new Date().valueOf() - startTime;
     var diffSecs = counterSecs - elapseSecs;
     nextelapse = normalelapse + diffSecs;
     diff.value = counterSecs + "-" + elapseSecs + "=" + diffSecs;
     next.value = "nextelapse = " + nextelapse;
     if (nextelapse < 0) nextelapse = 0;
     // 启动新的定时器
     timer = window.setInterval("onTimer()", nextelapse);
 }
 </script>

原文网址：http://www.nowamagic.net/librarys/veda/detail/421