window.onload = function() {
  communeUpdater = new SelectUpdater("commune", "cp.php?cp=", "msg_cp");
  ancienCp = "";
  document.getElementById("cp").onkeyup = function() {
    var cp = document.getElementById("cp").value;
    if ((cp.length == 5) && (!isNaN(cp))) {
      if (cp != ancienCp) {
        communeUpdater.run(cp);
        ancienCp = cp;
      }
    }
    else {
      communeUpdater.reset();
      ancienCp = "";
    }
  }
}