下面是另一种更少循环的方法:

calculateTotalMonthsDifference = function(firstDate, secondDate) {
        var fm = firstDate.getMonth();
        var fy = firstDate.getFullYear();
        var sm = secondDate.getMonth();
        var sy = secondDate.getFullYear();
        var months = Math.abs(((fy - sy) * 12) + fm - sm);
        var firstBefore = firstDate > secondDate;
        firstDate.setFullYear(sy);
        firstDate.setMonth(sm);
        firstBefore ? firstDate < secondDate ? months-- : "" : secondDate < firstDate ? months-- : "";
        return months;
}

function monthDiff(d1, d2) {
var months, d1day, d2day, d1new, d2new, diffdate,d2month,d2year,d1maxday,d2maxday;
months = (d2.getFullYear() - d1.getFullYear()) * 12;
months -= d1.getMonth() + 1;
months += d2.getMonth();
months = (months <= 0 ? 0 : months);
d1day = d1.getDate();
d2day = d2.getDate();
if(d1day > d2day)
{
    d2month = d2.getMonth();
    d2year = d2.getFullYear();
    d1new = new Date(d2year, d2month-1, d1day,0,0,0,0);
    var timeDiff = Math.abs(d2.getTime() - d1new.getTime());
          diffdate = Math.abs(Math.ceil(timeDiff / (1000 * 3600 * 24))); 
    d1new = new Date(d2year, d2month, 1,0,0,0,0);
    d1new.setDate(d1new.getDate()-1);
    d1maxday = d1new.getDate();
    months += diffdate / d1maxday;
}
else
{
      if(!(d1.getMonth() == d2.getMonth() && d1.getFullYear() == d2.getFullYear()))
    {
        months += 1;
    }
    diffdate = d2day - d1day + 1;
    d2month = d2.getMonth();
    d2year = d2.getFullYear();
    d2new = new Date(d2year, d2month + 1, 1, 0, 0, 0, 0);
    d2new.setDate(d2new.getDate()-1);
    d2maxday = d2new.getDate();
    months += diffdate / d2maxday;
}

return months;

}

我知道这真的很晚了，但还是把它贴出来，以防它能帮助到其他人。下面是我想出的一个函数，它似乎很好地计算了两个日期之间的月份差异。不可否认，这个方法比克劳德的方法要粗俗得多，但通过遍历日期对象提供了更准确的结果。它是在AS3中，但你应该能够放弃强类型，你会有JS。请随意让大家看起来更漂亮!

    function countMonths ( startDate:Date, endDate:Date ):int
    {
        var stepDate:Date = new Date;
        stepDate.time = startDate.time;
        var monthCount:int;

        while( stepDate.time <= endDate.time ) { 
            stepDate.month += 1;
            monthCount += 1;
        }           

        if ( stepDate != endDate ) { 
            monthCount -= 1;
        }

        return monthCount;
    }

任何值连同它的绝对值一起返回。

function differenceInMonths(firstDate, secondDate) {
    if (firstDate > secondDate) [firstDate, secondDate] = [secondDate, firstDate];
    let diffMonths = (secondDate.getFullYear() - firstDate.getFullYear()) * 12;
    diffMonths -= firstDate.getMonth();
    diffMonths += secondDate.getMonth();
    return diffMonths;
}
 

下面是另一种更少循环的方法:

calculateTotalMonthsDifference = function(firstDate, secondDate) {
        var fm = firstDate.getMonth();
        var fy = firstDate.getFullYear();
        var sm = secondDate.getMonth();
        var sy = secondDate.getFullYear();
        var months = Math.abs(((fy - sy) * 12) + fm - sm);
        var firstBefore = firstDate > secondDate;
        firstDate.setFullYear(sy);
        firstDate.setMonth(sm);
        firstBefore ? firstDate < secondDate ? months-- : "" : secondDate < firstDate ? months-- : "";
        return months;
}

function calcualteMonthYr(){
    var fromDate =new Date($('#txtDurationFrom2').val()); //date picker (text fields)
    var toDate = new Date($('#txtDurationTo2').val());

var months=0;
        months = (toDate.getFullYear() - fromDate.getFullYear()) * 12;
        months -= fromDate.getMonth();
        months += toDate.getMonth();
            if (toDate.getDate() < fromDate.getDate()){
                months--;
            }
    $('#txtTimePeriod2').val(months);
}