var xmlHttp
function showclass(str)

{
xmlHttp=GetXmlHttpObject();

if (xmlHttp==null)

  {

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

  return;

  } 

var url="getclass.php";

url=url+"?q="+str;

url=url+"&sid="+Math.random();

xmlHttp.onreadystatechange=stateChangedcity1;

xmlHttp.open("post",url,true);

xmlHttp.send(null);

}



function stateChangedcity1() 

{ 

if (xmlHttp.readyState==4)

{ 



document.getElementById("selectitem").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;

}