<html>
<head>
<meta charset="UTF-8">
<title>简单时长倒计时</title>
<SCRIPT type="text/javascript">
var maxtime = 60 * 5; //一个小时，按秒计算，自己调整!
function CountDown() {
if (maxtime >= 0) {
minutes = Math.floor(maxtime / 60);
seconds = Math.floor(maxtime % 60);
msg = minutes.pad(2) + ":" + seconds.pad(2);
document.all["timer"].innerHTML = msg;
--maxtime;
} else{
clearInterval(timer);
alert("时间到，结束!");
}
}
Number.prototype.pad = function(size) {
var s = String(this);
while (s.length < (size || 2)) {s = "0" + s;}
return s;
}
timer = setInterval("CountDown()", 1000);
</SCRIPT>
</head>
<body>
<div id="timer" style="color:red"></div>
<div id="warring" style="color:red"></div>
</body>
</html>