var xhr=GetXmlHttpObject();

function get_subcat_list() {
 	document.getElementById('scat2select').innerHTML="";
 	document.getElementById('scatselect').innerHTML="loading..."; 		
	var url="get_subcat_list.php";
	url += "?type=1";
	url += "&category="+document.getElementById('category').value;
	xhr.open("GET",url,true);
	xhr.onreadystatechange=get_subcat_list_response;
	xhr.send(null);
}

function get_subcat_list_response(){
	if (xhr.readyState==4 || xhr.readyState=="complete") { 
	    if (xhr.status == 200) {
			document.getElementById('scatselect').innerHTML=xhr.responseText;
		}
 		else {
 			alert("Get Subcategory Error: "+xhr.statusText);
 		}	 
 	} 
}

function get_subcat2_list() {
 	document.getElementById('scat2select').innerHTML="loading...";
	var url="get_subcat_list.php";
	url += "?type=2";
	url += "&category="+document.getElementById('category').value;
	url += "&subcategory="+document.getElementById('subcategory').value;
	xhr.open("GET",url,true);
	xhr.onreadystatechange=get_subcat2_list_response;
	xhr.send(null);
}

function get_subcat2_list_response() {
	if (xhr.readyState==4 || xhr.readyState=="complete") { 
	    if (xhr.status == 200) {
 			document.getElementById('scat2select').innerHTML=xhr.responseText;
		}
 		else {
 			alert("Get Sub-Subcategory Error: "+xhr.statusText);
 		}	 
 	} 
}

function reset_subcats() {
 	document.getElementById('scat2select').innerHTML="";
 	document.getElementById('scatselect').innerHTML=""; 		
}

function GetXmlHttpObject() {
	if (window.XMLHttpRequest) {
	    xhr_object = new XMLHttpRequest();
	}
	else if (window.ActiveXObject) {
		try {
			xhr_object = new ActiveXObject("Microsoft.XMLHTTP");
		}
		catch(e) {}
	}
	return xhr_object;
}