7 moi

<script language="javascript">
function populate_dest(f) {
  var l1    = f.elements["id_type_rdv"];
  var l2    = f.elements["id_dest"];
  var index = l1.selectedIndex;
  if(index < 1)
    l2.options.length = 0;
  else {
    var xhr_object = null;

    if(window.XMLHttpRequest) // Firefox
      xhr_object = new XMLHttpRequest();
    else if(window.ActiveXObject) // Internet Explorer
      xhr_object = new ActiveXObject("Microsoft.XMLHTTP");
    else { // XMLHttpRequest non supporté par le navigateur
      alert("Votre navigateur ne supporte pas les objets XMLHTTPRequest...");
      return;
    }

    xhr_object.open("POST", "phpToJs/users.inc.php", true);

    xhr_object.onreadystatechange = function() {
      if(xhr_object.readyState == 4)
        eval(xhr_object.responseText);
    }

    xhr_object.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    var data = "id_type_rdv="+escape(l1.options[index].value)+"&form="+f.name+"&select=id_dest";
    xhr_object.send(data);

  }
}
</script>

// Users.inc.php
echo 'var o = null;';
echo 'var s = document.forms["'.$_POST["form"].'"].elements["'.$_POST["select"].'"];';
echo 's.options.length = 0;';

while($res = mysql_fetch_array($exe)) {
  echo 's.options[s.options.length] = new Option("'.$res["us_nom"].'");';
}

// Error given
Erreur : missing ; before statement
Code source :
echo 'var o = null;';