js实现倒计时(距离结束还有)示例代码

<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>