JavaScript实现倒计时代码段Item1（非常实用）

<!DOCTYPE html>
<html>
<head>
 <title>获取时间</title>
 <script type="text/javascript">
 window.onload = function(){
  showTime();
 }
 function showTime(){
  var myDate = new Date();
  var year = myDate.getFullYear();
  var month = myDate.getMonth() + 1;
  var date = myDate.getDate();
  var dateArr = ["日","一",'二','三','四','五','六'];
  var day = myDate.getDay();
  var hours = myDate.getHours();
  var minutes = formatTime(myDate.getMinutes());
  var seconds = formatTime(myDate.getSeconds());
  var systemTime = document.getElementById("time");
  systemTime.innerHTML = " " + year + "年" + month +"月" + date + "日" + " 星期" + dateArr[day] + " " + hours + ":" + minutes + ":" + seconds;
  setTimeout("showTime()",500);
 }
 //格式化时间：分秒。
 function formatTime (i){
  if(i < 10){
   i = "0" + i;
  }
  return i;
 }
 </script>
</head>
<body>
 <div id ='time'></div>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
 <title>获取时间</title>
 <script type="text/javascript">
  window.onload = function(){
   deadTime();
  }
  function deadTime(){
   var nowTime = new Date();
   var finalTime = new Date("2015-11-11");
   var lefttime = (finalTime.getTime() - nowTime.getTime())/(1000*24*60*60);
   var date = Math.ceil(lefttime);
   document.getElementById("time").innerHTML = date;
  }
 </script>
</head>
<body>
 <div >距离双十一还有：<span id ='time'></span>天</div>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<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("2015/11/11,12:20:12");//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="距离活动结束还剩" + 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>