JS获取两个日期之间相差的天数

function  getDaysBetween(dateString1,dateString2){
   var  startDate = Date.parse(dateString1);
   var  endDate = Date.parse(dateString2);
   var days=(endDate - startDate)/(1*24*60*60*1000);
   // alert(days);
   return  days;
}