var lastDay = moment([year, month, daysInMonth]);
            var lastMonth = moment(firstDay).subtract(1, 'month').month();
            var lastYear = moment(firstDay).subtract(1, 'month').year();
            var daysInLastMonth = moment([lastYear, lastMonth]).daysInMonth();
            var dayOfWeek = firstDay.day();

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