var xmlHttp;

function verificaTermo(str)
{ 
xmlHttp=GetXmlHttpObject();
if (xmlHttp==null)
  {
  //alert ("Your browser does not support AJAX!");
  return;
  } 
textoEspera = '<select name="cidade"><option value="" selected>Carregando...&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</option></select>';  
document.getElementById("tb_cidade").innerHTML=textoEspera;
var url="pegaTermo.asp";
url=url+"?q="+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("tb_cidade").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;
}