"Hide" content

<script type="text/javascript">
var xmlHttp

function validate(str)
{
xmlHttp=GetXmlHttpObject();
if (xmlHttp==null)
  {
  alert ("Your browser does not support AJAX!");
  return;
  }
  document.getElementById("content").innerHTML='<p>&nbsp;</p><p>&nbsp;</p>'
  +'<center><h1>Thanking post!</h1><br /><img src="blablabla" alt="Loading..." /></center>';
var url="?add=1";
url=url+"?op="+str;
url=url+"&sid="+Math.random();
xmlHttp.onreadystatechange=stateChanged;
xmlHttp.open("GET",url,true);
xmlHttp.send(null);
}


function stateChanged()
{
if (xmlHttp.readyState==4)
{
document.getElementById("content").innerHTML=xmlHttp.responseText;
}
}

function GetXmlHttpObject()
{
var xmlHttp=null;
try
  {
  // Firefox, Opera 8.0+, Safari
  xmlHttp=new XMLHttpRequest();
  }
catch (e)
  {
  // Internet Explorer
  try
    {
    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    }
  catch (e)
    {
    xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
  }
return xmlHttp;
}
//-->
</script>

<button onclick="validate('')" id="button">TEST</button>