alter = new String
function berechne_alter (day_geb,mon_geb,jah_geb) {
  var now = new Date();
  var jah_akt = now.getYear();
  var mon_akt = now.getMonth()+1;
  var day_akt = now.getDate();

  alter = new String
  if (mon_akt > mon_geb) {
    alter = (jah_akt-jah_geb);
  }
  else {
    if (mon_akt < mon_geb) {
      alter = ((jah_akt-jah_geb)-1);
    }
    else {
      if (day_akt < day_geb) {
        alter = ((jah_akt-jah_geb)-1);
      }
      else {
        alter = (jah_akt-jah_geb);
      }
    }
  }
  //fix for Netscape//
  if (alter < 0) {
  alter = (alter + 1900);
  }
}