var req = null
function sub(f,target) {
	var url = '/catalog/index.php?action=prev_cart';
	var str = getFormValues(f);
	getXML(url,str,target);
}

function getXML(url,str,target) {
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
	} else if (window.ActiveXObject) {
		req = new ActiveXObject("Microsoft.XMLHTTP");
	}

	if (req) {
		req.onreadystatechange = function() {displayState(target);};
		req.open("POST", url, true);
		req.setRequestHeader("Content-Type","application/x-www-form-urlencoded; charset=UTF-8");
		req.send(str);
	}

}

function displayState(target) {
	if (req.readyState == 4) {
		if (req.status == 200) {
			var results = req.responseText;

			document.getElementById(target).innerHTML = results;
			return;
			
		}
	}
}


function getFormValues(fobj) {
	var str = "";
	var valueArr = null;
	var val = "";
	var cmd = "";
	for(var i = 0;i < fobj.elements.length;i++)  {
		switch(fobj.elements[i].type) {
			case "text":
				str += fobj.elements[i].name + "=" + escape(fobj.elements[i].value) + "&";
				break;
			case "select-one":
				str += fobj.elements[i].name + "=" + fobj.elements[i].options[fobj.elements[i].selectedIndex].value + "&";
				break;
			case "hidden":
				str += fobj.elements[i].name + "=" + escape(fobj.elements[i].value) + "&";
				break;
			case "checkbox":
				if (fobj.elements[i].checked) {			
					str += fobj.elements[i].name + "=on&";
				}
				break;
		}
	}
	str = str.substr(0,(str.length - 1));
	return str;
}