รบกวนขอความรู้หน่อยครับ โค้ด JavaScript มันค้างที่ Loading... ไม่ไปต่อ

// JavaScript Document
function Inint_AJAX() {
   try { return new ActiveXObject("Msxml2.XMLHTTP");  } catch(e) {} //IE
   try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch(e) {} //IE
   try { return new XMLHttpRequest(); } catch(e) {} //Native Javascript
   alert("XMLHttpRequest not supported");
   return null;
}

function DelProduct(element){
	var id=element;
	if (element=="delall"){
		var con="คุณต้องการลบรายการทั้งหมดหรือไม่";	
	}else{
	 	var con="คุณต้องการลบรายการนี้หรือไม่";
	}
	if(confirm(con)){
		var loading = '<img src="images/loading.gif"  style="padding:20px 0 0 200px;"> loading..';
		document.getElementById('loading').innerHTML= loading;
        var req = Inint_AJAX();
		req.onreadystatechange = function()	{
				if (req.readyState==4){
					if (req.status==200) {
						ListOrder(element);
					}
				}
		}
		var str="";
		str+="?name=products&file=shop&id="+id;
		str+="&op=del";
	
		
		var rstr;
		rstr=Math.random();
		str+="&var="+rstr;
			
		var url = "index.php"+str;
		req.open("GET", url, true);
		req.send(null);
	}
}
function Delall(){
	var con="คุณต้องการลบรายการทั้งหมดหรือไม่";	
	if(confirm(con)){
		var loading = '<img src="images/loading.gif"  style="padding:20px 0 0 200px;"> loading..';
		document.getElementById('loading').innerHTML= loading;		
        var req = Inint_AJAX();
		req.onreadystatechange = function()	{
				if (req.readyState==4){
					if (req.status==200) {
						//ListOrder(element);
						data = req.responseText;
						document.getElementById('viewcart').innerHTML = data;
					}
				}
		}
		var str="";
		str+="?name=products&file=shop";
		str+="&op=delall";
		
		var rstr;
		rstr=Math.random();
		str+="&var="+rstr;
			
		var url = "index.php"+str;
		req.open("GET", url, true);
		req.send(null);
	}
}

function ListOrder(element){
	
		var req = Inint_AJAX();	
		
		req.onreadystatechange = function()	{
				if (req.readyState==4){
					if (req.status==200) {
						data = req.responseText;
						document.getElementById('viewcart').innerHTML = data;
					}
				}
		}
		var id=element
		var str="";
		str+="?name=products&file=shop&op=viewcart";
		//str+="&id="+id;
		
		var rstr;
		rstr=Math.random();
		str+="&var="+rstr;
		req.open("GET","index.php"+str,true);
		req.send(null);
		return false;	
}


function UpdateQty(id,qty){
		if(isNaN(qty)){
			alert("ต้องเป็นตัวเลขเท่านั้น...  \nกรุณาตรวจสอบข้อมูลของท่านอีกครั้ง...");
			var thisfocus = "qty_"+id;
			document.getElementById(thisfocus).value="";
			return false;

		}else if(qty <= 0){
			alert("กรุณากรอตัวเลขมากกว่า 0 ");
			var thisfocus = "qty_"+id;
			document.getElementById(thisfocus).value="";
			return false;
		}else{
			var req = Inint_AJAX();	
			var loading = '<img src="images/loading.gif"  style="padding:20px 0 0 200px;"> loading..';
			document.getElementById('loading').innerHTML= loading;		
			req.onreadystatechange = function()	{
					if (req.readyState==4){
						if (req.status==200) {
							data = req.responseText;
							document.getElementById('viewcart').innerHTML = data;
						}
					}
			}
			var str="";
			str+="?name=products&file=shop&op=update&id="+id+"&quantity="+qty;
			
			var rstr;
			rstr=Math.random();
			str+="&var="+rstr;
			req.open("GET","index.php"+str,true);
			req.send(null);
			return false;
		}

}