一个js程序：离下一个圣诞节还有多少天？

//离下一个圣诞节还有多少天
var now=new Date();
var christ=new Date();
var year=now.getFullYear();
christ.setMonth(11);
christ.setDate(25);
var diff;
var theTime;
if(now.getTime()<=christ.getTime())
{
    diff=christ.getTime()-now.getTime();
    theTime=parseInt(diff/(24*60*60*1000));
}
else 
{
    christ=new Date((year+1)+"/12/25");//Date(datestring),Date(year,months,day,hours,minutes,seconds,ms),Date(milliseconds)
    diff=christ.getTime()-now.getTime();
    theTime=parseInt(diff/(24*60*60*1000));
}
document.write("离下一个圣诞节还有："+theTime+"天");