var xmlHttp

function showCustomer()
{ 
xmlHttp=GetXmlHttpObject();
if (xmlHttp==null)
  {
  alert ("ÄãµÄä¯ÀÀÆ÷²»Ö§³ÖAJAX!");
  return;
  } 
var obj=document.getElementById('yyb');
var index=obj.selectedIndex; 
var val = obj.options[index].value;
var vid=document.getElementById("khid").value;

var url="getcustomer.aspx";
url=url+"?ID="+vid;
url=url+"&yyb="+val;
xmlHttp.onreadystatechange=stateChanged;
xmlHttp.open("GET",url,true);
xmlHttp.send(null);
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4)
{ 
document.getElementById("btnMain").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;
}