function getHTTPObject(){

  if (window.ActiveXObject) 
  {
    return new ActiveXObject("Microsoft.XMLHTTP");
  }
  else if (window.XMLHttpRequest) 
  {
    return new XMLHttpRequest();
  }
  else 
  {

    alert("Your browser does not support AJAX.");

      return null;

    }

}

function searchSite(){

    httpObject = getHTTPObject();

    if (httpObject != null) 
    {

      httpObject.open("GET", "search.php5?q="+document.getElementById("searchbox").value, true);

      httpObject.send(null);
      httpObject.onreadystatechange = setOutput;

    }
}

function setOutput(){

  if(httpObject.readyState == 4)
  {
      document.getElementById('content_div').innerHTML = httpObject.responseText;
  }
}