var daysInLastMonth = moment([lastYear, lastMonth]).daysInMonth();
            var dayOfWeek = firstDay.day();

            //initialize a 6 rows x 7 columns array for the calendar
            var calendar = [];
            calendar.firstDay = firstDay;
            calendar.lastDay = lastDay;

            for (var i = 0; i < 6; i++) {
                calendar[i] = [];