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;
}