var xmlHttp  
function show(str)  {
   xmlHttp=GetXmlHttpObject() 
     if (xmlHttp==null)   {
       alert ("Browser does not support HTTP Request")   return   
     }  
   var url="getuser.php"
   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 || xmlHttp.readyState=="complete")
   {    document.getElementById("txtHint").innerHTML=xmlHttp.responseText   }
}
function GetXmlHttpObject()  {
   var xmlHttp=null;
   try   {
   xmlHttp=new XMLHttpRequest();
   }  catch (e)   {
   try    {
   xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
   }   catch (e)    {
   xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
   }
 }
  return xmlHttp;
}