// JavaScript Document
function CreateXHR()
{
var request;
var browser = navigator.appName;
//使用IE，则使用XMLHttp对象
if(browser == "Microsoft Internet Explorer")
{
    var arrVersions = ["Microsoft.XMLHttp", "MSXML2.XMLHttp.4.0",
      "MSXML2.XMLHttp.3.0", "MSXML2.XMLHttp","MSXML2.XMLHttp.5.0"];
    for (var i=0; i < arrVersions.length; i++)
    {
      try
      {
//从中找到一个支持的版本并建立XMLHttp对象
        request = new ActiveXObject(arrVersions[i]);
        return request;
      }
      catch(exception)
      {
         //忽略，继续
      }
    }
}
else
{
    //否则返回一个XMLHttpRequest对象
    request = new XMLHttpRequest();
  
    return request;
}  
}

var Request = new CreateXHR();//实例化

function ShowCategory(x)
{
   var URL = "Category.php?value=" + x;   

  
   Request.open("GET",URL,true);
    
   Request.onreadystatechange = Showphoto_subcategory;
  
   Request.send(null);
}
function Showphoto_subcategory()
{
   if(Request.readyState == 4 && Request.status == 200)
   {
         
    document.getElementById("photo_subcategory").style.display = '';
   
    //读取返回的xml数据
    var myData = Request.responseXML.getElementsByTagName("row");
   
        if(myData.length == 0)
    {
    document.getElementById("photo_subcategory").options[0] = new Option("------","");
    }
   
    var myStr = new Array(); //创建一数组用来存放text
   
    var myValue = new Array();   //创建一数据用来存放value
       
    for(var i = 0;i<myData.length;i++)
     {
         
      myStr[i] = myData[i].firstChild.data;
      myValue[i] = myData[i].getAttribute("value");
                 
     }
    
    document.getElementById("photo_subcategory").options.length = 0;   
	document.getElementById("photo_subcategory").options[0] = new Option("----------","");
   
    for(var j = 0;j<myStr.length;j++)
     {
      document.getElementById("photo_subcategory").options[document.getElementById("photo_subcategory").options.length] = new Option(myStr[j],myValue[j]);
     }
    
   }
   
}