How to add Month or Day with a Date in JQuery?

//.....Add 1 month From Selected Date

AddMonthToDate: function (selectedDate, month) {
     
        var date = new Date(selectedDate);
        var currentDate = date.getDate();
        date.setDate(month);
        date.setMonth(date.getMonth() + month);
        var daysInMonth = new Date(date.getYear(), date.getMonth() + month, 0).getDate();
        date.setDate(Math.min(currentDate, daysInMonth));
        return date;
    },
  

//...Add 30 Days From Selected Date

    AddDaysToDate: function (selectedDate, days) {
   
        var x = selectedDate.getDate();
        var m1 = selectedDate.getMonth();
        selectedDate.setDate(selectedDate.getDate() + days);
        var m2 = selectedDate.getMonth();
        if (m1 == m2) {
            selectedDate.setDate(selectedDate.getDate() + 1);
        }
        return new Date(selectedDate);
    }