SQL Join Help....

Set date after adding month

Set date after adding month 

 var firstdate = document.getElementById('<%= txtdoj.ClientID %>').value;
            var period = document.getElementById('<%= txtproperiod.ClientID %>').value;

var set_start = firstdate.split('/');

            var day = set_start[0];
            var month = (set_start[1] - 1);  // January is 0 so August (8th month) is 7
            var year = set_start[2];
            var datetime = new Date(year, month, day);
            var newmonth = (month + parseInt(period));  // Must convert term to integer
            var newdate = datetime.setMonth(newmonth);

            newdate = new Date(newdate);
            //alert(newdate);

            day = newdate.getDate();
            month = newdate.getMonth() + 1;
            year = newdate.getFullYear();

            // This is British date format. See below for US.
            calcval = (((day <= 9) ? "0" + day : day) + "/" + ((month <= 9) ? "0" + month : month) + "/" + year);

            // mm/dd/yyyy
            calcval = (((month <= 9) ? "0" + month : month)+ "/" + ((day <= 9) ? "0" + day : day)  + "/" + year);