javascript pretty date difference with year, month, day

nachoDateDiff.js

function nachoDateDiff(startDate, endDate)
{
    // if start date is past end date stop
    if(startDate > endDate) return null;
    
    // calc the various start/end dates
    var sy = startDate.getFullYear(),
        ey = endDate.getFullYear(),
        sm = startDate.getMonth(),
        em = endDate.getMonth(),
        sd = startDate.getDate(),
        ed = endDate.getDate();
    
    // find the difference
    var years = ey - sy;
    var months = em - sm;
    var days = ed - sd;
    
    // if month is negative we need to go back one year and find the new months
    if(months < 0)
    {
        years--;
        months += 12;
    }
    
    // if days is negative we need to go back one month and find the right days
    if(days < 0)
    {
        months--;
        days += (new Date(ey, em + 1, 0).getDate());
    }
    
    // return
    return [years, months, days];
}

// example
nachoDateDiff(new Date(2016,5,15), new Date(2019,3,10)); // [2, 9, 25]