function changedate (fieldid, action){


var dodate = document.getElementById(fieldid).value;

if (dodate)
{




        var dodatearr = dodate.split(".");

        var d31=new Date(dodatearr[2], dodatearr[1]-1, dodatearr[0]);

        if (action == 'add') { d31.setDate(d31.getDate()+1);  }
        if (action == 'sub') { d31.setDate(d31.getDate()-1);   }  

        newday = d31.getDate();
        newmonth = d31.getMonth() + 1;
        newyear = d31.getFullYear();

        newdate = newday + "." + newmonth + "." + newyear;

        var dodate2 = document.getElementById(fieldid);
        
        dodate2.value = newdate;

}

}