var xmlHttp

function selectSubCat(maincat)
   { 
   xmlHttp=GetXmlHttpObject()
   if (xmlHttp==null)
      {
      alert ("Browser does not support HTTP Request");
      return;
      }
   var url="loadsubcat.php?";
   url=url+"maincat="+maincat;
   xmlHttp.onreadystatechange=stateChanged 
   xmlHttp.open("GET",url,true)
   xmlHttp.send(null)
   }

function stateChanged() 
   { 
   if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
      {       
      document.getElementById("sub_category1").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;
   }