gistfile1.txt

function getXml(url, cb) {
	var xhr = new XMLHttpRequest();
	xhr.open("GET", url, true);
	xhr.onreadystatechange = function (e) {
		if (xhr.readyState == 4) {
			var code = xhr.status;
			if (code >= 200 && code < 400) {
				cb(null, xhr.responseXML);
			} else {
				var err = new Error(xhr.responseText);
				err.code = code;
				cb(err);
			}
		}
	};
	xhr.send();
}