var request = null;

function createRequest() {
 try {
   request = new XMLHttpRequest();
 } catch (trymicrosoft) {
   try {
	 request = new ActiveXObject("Msxml2.XMLHTTP");
   } catch (othermicrosoft) {
	 try {
	   request = new ActiveXObject("Microsoft.XMLHTTP");
	 } catch (failed) {
	   request = null;
	 }
   }
 }

if (request == null)
   alert("Error creating request object!");
}

/* check username exists etc */

function checkUsernameExists() {
 createRequest();
 var username = document.getElementById("userexists").value;
 var url = "ajax.php?action=userexists&username=" + escape(username);
 request.open("GET", url, true);
 request.onreadystatechange = updatePage;
 request.send(null);
}

function updatePage() {
	if (request.readyState == 4) {
		if(request.Status = 200) {
		  var status = request.responseText;
		  document.getElementById("status").innerHTML = status;
		}
	}
}

/* Shopping Cart */

function addcart(id) {
	createRequest();
	var url = "ajax.php?action=addcart&id=" + id;
	request.open("GET", url, true);
	request.onreadystatechange = updateCart;
	request.send(null);
}

function updateCart() {
	if (request.readyState == 4) {
		if(request.Status = 200) {
		  var status = request.responseText;
		  document.getElementById("cart").innerHTML = status;
		}
	}
}