js实现倒计时

<SCRIPT LANGUAGE="JavaScript">

<!--

var maxtime = 60*60;//60*60 //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 = "距离结束还有"+minutes+"分"+seconds+"秒";

msg = "距离结束还有"+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!");

maxtime=60*60;

timer = setInterval("CountDown()",1000);

}

}

timer = setInterval("CountDown()",1000);

//-->

</SCRIPT>

<div id="timer" style="color:red"></div>

<SCRIPT LANGUAGE="JavaScript">

<!--

var maxtime = 5*60;//60*60 //一个小时，按秒计算，自己调整!

var timer;

function CountDown(){

if(maxtime>=0){

var minutes = Math.floor(maxtime/60);

var seconds = Math.floor(maxtime%60);

var msg = "距离刷新还有"+minutes+"分"+seconds+"秒";

$('#timer').html(msg);

//document.all["timer"].innerHTML=msg;

--maxtime;

}else{

clearInterval(timer);

//一下两个方法是倒计时结束后调用的方法

searchTaskList();

myajax();

//设置下一次的倒计时

maxtime=5*60;

timer = setInterval("CountDown()",1000);

}

}

timer = setInterval("CountDown()",1000);

//-->

</SCRIPT>

<div id="timer" style="display:inline;color:red"></div>