js如何计算两个日期，差几个月零几天？

Question

如果这样写的话，会出现负数24个月，-1天啊function monthDayDiff(startDate,endDate){ start = new Date(startDate);let end = new Date(endDate);    end.setDate(end.getDate()+1);let year=end.getFullYear()-start.getFullYear();let month=end.getMonth()-start.getMonth();let day=end.getDate()-start.getDate();let data = new Array(12*year+month,day) ;return data;}console.log(monthDayDiff('2017-3-3','2019-3-1'));