时间差计算

  showdaytext : function(time){
                  var showday = {
                      "1" : "一天后开始",
                      "2" : "两天后开始",
                      "3" : "三天后开始",
                  };
                  var  upday = new Date(time).getTime() - new Date().getTime();
                  var hours = Math.abs(Math.floor((upday % (24*3600*1000))/(3600*1000)));
                  var day = Math.abs(Math.floor(upday/(24*3600*1000)));
if(upday>0) {
   if(day==0) {
      return  1;
   }
   if(day==1) {
      return  2;
   }
   if(day==2) {
      return  3;
   }
}



              },