JQ倒计时天时分秒

<div id="times_wrap" class="time_num"> 
距离现在时间： 
<div class="time_w"> 
<span id="time_d" class="time"> </span >天 
<span id="time_h" class="time"> </span >时 
<span id="time_m" class="time"> </span >分 
<span id="time_s" class="time"> </span >秒 
</div> 
</div> 

<script type="text/javascript"> 
$(function(){ 

show_time(); 

}); 

function show_time(){ 
var time_start = new Date("2013/10/01 00:00:00").getTime();//设定开始时间 
var time_end = new Date().getTime(); //设定结束时间(等于系统当前时间) 
//计算时间差 
var time_distance = time_end - time_start; 
if(time_distance > 0){ 
// 天时分秒换算 
var int_day = Math.floor(time_distance/86400000) 
time_distance -= int_day * 86400000; 

var int_hour = Math.floor(time_distance/3600000) 
time_distance -= int_hour * 3600000; 

var int_minute = Math.floor(time_distance/60000) 
time_distance -= int_minute * 60000; 

var int_second = Math.floor(time_distance/1000) 
// 时分秒为单数时、前面加零 
if(int_day < 10){ 
int_day = "0" + int_day; 
} 
if(int_hour < 10){ 
int_hour = "0" + int_hour; 
} 
if(int_minute < 10){ 
int_minute = "0" + int_minute; 
} 
if(int_second < 10){ 
int_second = "0" + int_second; 
} 
// 显示时间 
$("#time_d").html(int_day); 
$("#time_h").html(int_hour); 
$("#time_m").html(int_minute); 
$("#time_s").html(int_second); 

setTimeout("show_time()",1000); 

}else{ 
$("#time_d").html('00'); 
$("#time_h").html('00'); 
$("#time_m").html('00'); 
$("#time_s").html('00'); 

} 
} 
</script>