Frage zu AJAX und Opera

[Sascha79]

var XMLHTTP = null;

if(window.XMLHttpRequest)
{
 XMLHTTP = new XMLHttpRequest();
}
else if(window.ActiveXObject)
{
 try
 {
  XMLHTTP = new ActiveXObject("Msxml2.XMLHTTP");
 }
 catch(e)
 {
  try
  {
   XMLHTTP = new ActiveXObject("Microsoft.XMLHTTP");
  }
  catch(e)
  {
   XMLHTTP = null;
  }
 }
}

function alterForumEntry(foid, mode)
{
 if(mode == 'textarea')
 {
  XMLHTTP.open("GET", "/networks/alterEntry.php?foid="+foid+"&mode=1");
  XMLHTTP.onreadystatechange = function() { sendAlterForumEntry(foid); };
  XMLHTTP.send(null);
 }
 else if(mode == 'update')
 {
  var text = document.getElementById("text"+foid).value;

if(text.trim() == '')
  {
   return alert('Du hast kein Text angegeben.');
  }

XMLHTTP.open("POST", "/networks/alterEntry.php?foid="+foid+"&mode=2");
  XMLHTTP.onreadystatechange = function() { sendAlterForumEntry(foid); };
  XMLHTTP.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
  XMLHTTP.send("text="+encodeURI(text));
 }
 else if(mode == 'cancel')
 {
  XMLHTTP.open("GET", "/networks/alterEntry.php?foid="+foid+"&mode=3");
  XMLHTTP.onreadystatechange = function() { sendAlterForumEntry(foid); };
  XMLHTTP.send(null);
 }
}

function sendAlterForumEntry(foid)
{
 var Container = document.getElementById('alterComment'+foid);

if(XMLHTTP.readyState < 4)
 {
  Container.innerHTML = '<div style="text-align:center; height:60px; padding-top:20px;"><img src="/images/loading.gif" width="32" height="32" alt="Daten werden geladen..." style="margin-bottom:10px;"><br />Daten werden geladen...</div>';
 }

if(XMLHTTP.readyState == 4)
 {
  var Container = document.getElementById('alterComment'+foid);
  Container.innerHTML = XMLHTTP.responseText;
 }
}