为网站添加运行天数Js

function show_date_time(t){  
window.setTimeout("show_date_time()", 1000);  
BirthDay=new Date(t);
today=new Date();  
timeold=(today.getTime()-BirthDay.getTime());  
sectimeold=timeold/1000;
secondsold=Math.floor(sectimeold);  
msPerDay=24*60*60*1000;
e_daysold=timeold/msPerDay;
daysold=Math.floor(e_daysold);  
e_hrsold=(e_daysold-daysold)*24;
return daysold;  
}