$(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');

}
}