function ajax(url)
{
 req = null;
 if (window.XMLHttpRequest) 
 {
	req = new XMLHttpRequest();
	req.onreadystatechange = processReqChange;
	req.open("GET",url,true);
	req.send(null);
 } 
 else if (window.ActiveXObject) 
 {
	req = new ActiveXObject("Microsoft.XMLHTTP");
	if (req) 
	{
		req.onreadystatechange = processReqChange;
		req.open("GET",url,true);
		req.send();
	}
 }
}

function processReqChange()
{
 if (req.readyState == 4) 
 {
  if (req.status ==200) 
  {
   document.getElementById('busca').innerHTML = req.responseText;
  } 
  else 
  {
   alert("Houve um problema ao obter os dados:n" + req.statusText);
  }
 }
}