function ajax(url){

 var xmlHttp;
 
 try
 {
  // Firefox, Opera 8.0+, Safari
  xmlHttp=new XMLHttpRequest();
 }
 catch (e)
 {
  // Internet Explorer
  try
  {
    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
  }
  catch (e)
  {
    try
    {
      xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
    catch (e)
    {
      alert("Your browser does not support AJAX!");
      return false;
    }
  }
  }

 
 xmlHttp.onreadystatechange=function(){
  if(xmlHttp.readyState==4 && xmlHttp.status==200){
     document.getElementById('tartalom').innerHTML=xmlHttp.responseText;
  }
 }
 xmlHttp.open('get',url,true);
 xmlHttp.send(null);
}