var currentDate = new Date(); var currentYear = 1900 + currentDate.getYear();
    var dailyMS = 24*60*60*1000;
    var arrivalDate = new Date(currentDate.getTime());
    var departureDate = new Date(currentDate.getTime() + 1*dailyMS);
    var arrivalYear = 1900+arrivalDate.getYear();
    var arrivalMonth = 1+arrivalDate.getMonth(); var arrivalDay = arrivalDate.getDate();
    var departureYear = 1900+departureDate.getYear();
    var departureMonth = 1+departureDate.getMonth(); var departureDay = departureDate.getDate();
    var a=document.frm;
    if ((a.checkin_monthday.selectedIndex == 0) && (a.checkout_monthday.selectedIndex == 0)){
        a.checkin_monthday.options[arrivalDay-1].selected = true;
        a.checkout_monthday.options[departureDay-1].selected = true;
    }

        var frm = document.getElementById('frm');
                // create date object from checkin values
                // set date to 12:00 to avoid problems with one
                // date being wintertime and the other summertime
        var my = frm['b_checkin_month'].value.split("-");
           var ci = new Date (my[0], my[1]-1, frm['b_checkin_day'].value, 12, 0, 0, 0);

        // create date object from checkout values
         my = frm['b_checkout_month'].value.split("-");
         var co = new Date (my[0], my[1]-1, frm['b_checkout_day'].value, 12, 0, 0, 0);
        if (ci >= co){
            co.setTime(ci.getTime() + 1000 * 60 * 60 * 24);
                frm['b_checkout_day'].value =  co.getDate();
            var com = co.getMonth()+1;
                frm['b_checkout_month'].value = co.getFullYear() + "-" + com;
    }