js倒计时

var _time;
var interval = 1000;
function ShowCountDown(year,month,day,hours, minutes, seconds,divname){
var now = new Date();
var endDate = new Date(year, month-1, day,hours,minutes,seconds);
var leftTime=endDate.getTime()-now.getTime();
var leftsecond = parseInt(leftTime/1000);
//var day1=parseInt(leftsecond/(24*60*60*6));
var day1=Math.floor(leftsecond/(60*60*24));
var hour=Math.floor((leftsecond-day1*24*60*60)/3600);
var minute=Math.floor((leftsecond-day1*24*60*60-hour*3600)/60);
var second=Math.floor(leftsecond-day1*24*60*60-hour*3600-minute*60);
var cc = document.getElementById(divname);
cc.innerHTML = "距离"+year+"年"+month+"月"+day+"日"+hours+"时"+minutes+"分"+seconds+"秒还有："+day1+"天"+hour+"小时"+minute+"分"+second+"秒";
if(second==0){
alert('活动结束啦！');
window.clearInterval(_time);
}
}
_time=window.setInterval(function(){ShowCountDown(2015,12,01,15,35,00,'divdown1');}, interval);