JavaScript 实现网页倒计时功能的两种实例代码

<html> 
 <head> 
  <title>倒计时</title> 
  <!--以下为css样式--> 
  <style type= "text/css"> 
   .daojishi h2 
   { 
    font-family:Helvetica, Microsoft YaHei, Arial, sans-serif; 
    font-size:14px; 
    margin-bottom:5px; 
    color:#151515; 
   } 
   .daojishi #timer 
   { 
    font-family:Helvetica, Microsoft YaHei, Arial, sans-serif; 
    font-size:14px; 
    color:#151515; 
    font-weight:bold; 
   } 
  </style> 
  <script type = "text/javascript" src = "timer.js"> 
  </script> 
 </head> 
 <body onload = "timer()"> 
  <div class = "daojishi"> 
   <h2>剩余时间为：</h2> 
   <div id = "timer"> 
   </div> 
  </div> 
 </body> 
</html>

function timer() 
{
 var ts = (new Date(2018, 11, 11, 9, 0, 0)) - (new Date());//计算剩余的毫秒数
 var dd = parseInt(ts / 1000 / 60 / 60 / 24, 10);//计算剩余的天数
 var hh = parseInt(ts / 1000 / 60 / 60 % 24, 10);//计算剩余的小时数
 var mm = parseInt(ts / 1000 / 60 % 60, 10);//计算剩余的分钟数
 var ss = parseInt(ts / 1000 % 60, 10);//计算剩余的秒数
 dd = checkTime(dd);
 hh = checkTime(hh);
 mm = checkTime(mm);
 ss = checkTime(ss);
 document.getElementById("timer").innerHTML = dd + "天" + hh + "时" + mm + "分" + ss + "秒";
 setInterval("timer()",1000);
}
function checkTime(i)
{
  if (i < 10) {
  i = "0" + i;
 }
  return i;
}

<!doctype html>
<html>
<head>
 <meta charset="utf-8">
 <title>倒计时js代码</title>
</head>
<body>
<DIV id="CountMsg" class="HotDate">
 <span id="t_d">00天</span>
 <span id="t_h">00时</span>
 <span id="t_m">00分</span>
 <span id="t_s">00秒</span>
</DIV>
<script type="text/javascript">
 function getRTime(){
  var EndTime= new Date('2016/05/1 10:00:00'); //截止时间
  var NowTime = new Date();
  var t =EndTime.getTime() - NowTime.getTime();
  /*var d=Math.floor(t/1000/60/60/24);
  t-=d*(1000*60*60*24);
  var h=Math.floor(t/1000/60/60);
  t-=h*60*60*1000;
  var m=Math.floor(t/1000/60);
  t-=m*60*1000;
  var s=Math.floor(t/1000);*/
  var d=Math.floor(t/1000/60/60/24);
  var h=Math.floor(t/1000/60/60%24);
  var m=Math.floor(t/1000/60%60);
  var s=Math.floor(t/1000%60);
  document.getElementById("t_d").innerHTML = d + "天";
  document.getElementById("t_h").innerHTML = h + "时";
  document.getElementById("t_m").innerHTML = m + "分";
  document.getElementById("t_s").innerHTML = s + "秒";
 }
 setInterval(getRTime,1000);
 </script>
</body>
</html>