/**
 * 倒计时
 * 2017年2月16日 11:54:23
 */
function countDown(){
	if($("#end_time").val()!=null&&$("#end_time").val()!=''){
		var day_elem = $(".js-day");
		var hour_elem = $(".js-hour");
		var minute_elem = $(".js-min");
		var second_elem = $(".js-sec");
		var end_time = new Date($("#end_time").val()).getTime(),//月份是实际月份-1 
		sys_second = (end_time-new Date().getTime())/1000;
		if(sys_second>1){
			sys_second -= 1;
			var day = Math.floor((sys_second / 3600) / 24);
			var hour = Math.floor((sys_second / 3600) % 24);
			var minute = Math.floor((sys_second / 60) % 60);
			var second = Math.floor(sys_second % 60);
			day_elem && $(day_elem).text(day);//计算天
			$(hour_elem).text(hour<10?"0"+hour:hour);//计算小时 
			$(minute_elem).text(minute<10?"0"+minute:minute);//计算分钟 
			$(second_elem).text(second<10?"0"+second:second);//计算秒杀 
		}
		var timer = setInterval(function(){
			if (sys_second > 1) {
				sys_second -= 1;
				var day = Math.floor((sys_second / 3600) / 24);
				var hour = Math.floor((sys_second / 3600) % 24);
				var minute = Math.floor((sys_second / 60) % 60);
				var second = Math.floor(sys_second % 60);
				day_elem && $(day_elem).text(day);//计算天
				$(hour_elem).text(hour<10?"0"+hour:hour);//计算小时 
				$(minute_elem).text(minute<10?"0"+minute:minute);//计算分钟 
				$(second_elem).text(second<10?"0"+second:second);//计算秒杀 
			} else { 
				clearInterval(timer); 
			}
		}, 1000);
	}
}