javascript计算两个日期之间相差几个月份

function checkTime(obj){  
      var startTime= $(obj).parent().siblings().next().next().children().val();//到项目时间
      var endTime= $(obj).parent().siblings().next().next().next().children().val();//离项目时间
      var startDate=new Date(startTime.replace("-", "/").replace("-", "/"));  
      var endDate=new Date(endTime.replace("-", "/").replace("-", "/"));  

      var number = 0;    
      var yearToMonth = (endDate.getFullYear() - startDate.getFullYear()) * 12;    
      number += yearToMonth;    
      monthToMonth = endDate.getMonth() - startDate.getMonth();    
      number += monthToMonth;    
     //endDay = endDate.getDate();    
     //startDay = startDate.getDate();    
     //dayStep = endDay - startDay;    
     //if (dayStep >= 0) {    
     //    if (dayStep >= 15) {    
     //        number += 1;    
     //    }    
     //} else {    
     //    if (dayStep <= -15) {    
     //        number -= 1;    
     //    }    
     //} 
     $(obj).blur();
     alert(parseInt(number  + 1) + " 人月 ");
     return false;
}