var xmlhttp;
function loadXMLDoc(url) {
  xmlhttp=null;
  if (window.XMLHttpRequest) { // code for Firefox, Opera, IE7, etc.
    xmlhttp=new XMLHttpRequest();
  }
  else if (window.ActiveXObject) { // code for IE6, IE5
    xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
  if (xmlhttp!=null) {
    xmlhttp.onreadystatechange=state_Change;
    xmlhttp.open("GET",url,true);
    xmlhttp.send(null);
  }
  else {
    alert("Your browser does not support XMLHTTP.");
  }
}

function state_Change() {
  if (xmlhttp.readyState==4) { // 4 = "loaded"
    if (xmlhttp.status==200) { // 200 = "OK"
      document.getElementById('contentsection').innerHTML=xmlhttp.responseText;
    }
    else
    {
      alert("Problem retrieving data:" + xmlhttp.statusText);
    }
  }
}