// JavaScript Document
var selObj;
function ajxGetOption(sel){
  selObj= new Array();
  var fm= document.getElementById("cajaxform");
  var a= Array();
  var i, x, y, s= Array();
  for (i=0; i< fm.elements.length; i++){
    if (fm.elements[i].tagName=="SELECT") selObj.push(fm.elements[i]);
  }
  for (x in selObj){
    y= selObj[x].selectedIndex<0?-1:selObj[x].options[selObj[x].selectedIndex].value;
    s.push(selObj[x].id.substr(1) + "=" + y);
  }
  x=s.join("&");

     var xmlHttp= new ajaxobj();
     if (xmlHttp==false){
        alert("You browser not support ajax");
        return;
     }
     
     xmlHttp.onreadystatechange=function(){
        ajxUpdateOption(xmlHttp);
     }
 
     var qa=ajxQueryArray();
     var q= "../ajxSelect.php?"+ x + "&x=" + qa["x"];
     xmlHttp.open("GET", q, true);
     xmlHttp.send(null);

} //ajxOption

function ajxQueryArray(){
  var qa= new Array();
  var qry =location.search.substring(1);
  var a=qry.split('&')

  for (var i=0; i<a.length; i++) {
     var p = a[i].indexOf('=');
    if (p > 0) {
       var key = a[i].substring(0,p);
       var val = a[i].substring(p+1);
       qa[key] = val;
    }
  }
  
  return qa;
} // ajxQueryArray


function ajxUpdateOption(xmlHttp){
  var rt, a;
  var fm= document.getElementById("cajaxform");
        if(xmlHttp.readyState==4){
         if (xmlHttp.responseText==""){
            alert('empty response');
         }else{
            rt= xmlHttp.responseText;
//alert(rt);
//            if (document.all){
//              ajxIESnail(rt);
//            }else{
              a= rt.split("<$>");
              for (i in a){
                 selObj[i].parentNode.innerHTML=a[i];
              }
//            }
         }
        }
} // ajxUpdateOption


function ajxIESnail(opts){
  var a= opts.split("<$>");
  var s= '<select name="category" id="chanpin1" onchange="xGetOption(this, 1);">'
        +a[0]
        +'</select>'
        
        +'<select name="category" id="chanpin2" onchange="xGetOption(this, 2);">'
        +a[1]
        +'</select>' 
        
        +'<select name="category" id="chanpin3" onchange="xGetOption(this, 3);">'
        +a[2]
        +'</select>';
  var sel = document.getElementById("chanpin1"); 
  var d=sel.parentNode;
  d.innerHTML=s;  
  return;   
} // xIESnail