setInterval("t('2018/5/21 12:00:00',day,hours,minutes,seconds)",500);
function t(expire_time,d,h,m,s) {
var $Day = $(d),
$Hours = $(h),
$Minutes = $(m),
$Seconds = $(s),
NowTime = new Date(),
EndTime = new Date(expire_time),
t = (EndTime.getTime() - NowTime.getTime()),
day = Math.floor(t / 1000 / 60 / 60 / 24),
hours = Math.floor(t / 1000 / 60 / 60 % 24),
minutes = Math.floor(t / 1000 / 60 % 60),
seconds = Math.floor(t / 1000 % 60);
$Day.html(day < 10 ?(day<0 ?'00':'0'+day):day);
$Hours.html( hours < 10 ?(hours<0 ?'00':'0'+hours):hours);
$Minutes.html( minutes < 10 ?(minutes<0 ?'00':'0'+minutes):minutes);
$Seconds.html( seconds < 10 ?(seconds<0 ?'00':'0'+seconds):seconds);
}