function ajaxRequest(){
 var activexmodes=["Msxml2.XMLHTTP", "Microsoft.XMLHTTP"] //activeX versions to check for in IE
 if (window.ActiveXObject){ //Test for support for ActiveXObject in IE first (as XMLHttpRequest in IE7 is broken)
  for (var i=0; i<activexmodes.length; i++){
   try{
    return new ActiveXObject(activexmodes[i])
   }
   catch(e){
    //suppress error
   }
  }
 }
 else if (window.XMLHttpRequest) // if Mozilla, Safari etc
  return new XMLHttpRequest()
 else
  return false
}

function ajaxFunction() {	
	
	var subCatSelected = getVar('subcat');
	document.content.subcatmenu.disabled =true;
	myRand=parseInt(Math.random()*99999999);  // cache buster
	var output = '';
	var mygetrequest=new ajaxRequest()
	mygetrequest.onreadystatechange=function(){
	
	 if (mygetrequest.readyState==4){
	  if (mygetrequest.status==200 || window.location.href.indexOf("http")==-1) {
	   var jsonData=eval("("+mygetrequest.responseText+")"); //retrieve result as an JavaScript object
	    // alert(mygetrequest.responseText);
		 subCats = jsonData.subcat;
		// alert(jsonData.url.value);
		if (document.content.catmenu.value !='')
			document.content.subcatmenu.disabled = false;
	   for (var i=0; i<jsonData.subcat.length; i++){
			document.content.subcatmenu.options[i] = new Option(subCats[i].title,subCats[i].id);
			if (subCatSelected == subCats[i].id)
				document.content.subcatmenu.options[i].selected = true
		}
	  }
	  else{
	   alert("An error has occured making the request")
	  }
	 }
	}
	
	urlString = "http://www.roadsonline.com.au/inc/json.php?mainCatid="+document.content.catmenu.value+"&rand="+parseInt(myRand);
	mygetrequest.open("GET",urlString , true)
	mygetrequest.send(null)

	
 }