<script type="text/javascript">
var maxtime = 1350057600 //截止到的日期
var now=parseInt((new Date().getTime())/1000);//获取当前的日期
var cha_time=maxtime-now;//中间所差的时间

下面方法把相差的时间组合成倒计时的字符串，然后放到页面相应位置实现，实时刷新
function CountDown(){  
if(cha_time>=0){
var day = Math.floor(cha_time/3600/24);
var hour= Math.floor((cha_time/3600)%24);
var minutes = Math.floor((cha_time/60)%60);  
var seconds = Math.floor(cha_time%60);  
msg = "离结束还有"+day+"天"+hour+"小时"+minutes+"分"+seconds+"秒"; 
$(".ws_sg_con_big,.ws_sg_con_small").find("dd").html(msg);
--cha_time;  
}  
else{  
clearInterval(timer);  
alert("时间到，结束!");  
}  
}  
timer = setInterval("CountDown()",1000); 
</script>