How to access XML element by attribute id?

app.js

var self = Ti.UI.createWindow({
	backgroundColor : '#fff'
});
var xhr = Titanium.Network.createHTTPClient();
var aTableView = Ti.UI.createTableView();
xhr.onload = function() {

	//Ti.API.info('http://appc.mrtechnologybd.com/node.xml ' + this.responseXML + ' text ' + this.responseText);

	var doc = this.responseXML.documentElement;

	var data = [];
	var items = doc.getElementsByTagName("animal");
	for (var i = 0; i < items.length; i++) {

		var type = items.item(i).getElementsByTagName("type").item(0).getAttribute('id');
		data.push({
			title : type
		});
	}

	aTableView.setData(data);

	self.add(aTableView);

};

xhr.onerror = function(e) {
	Ti.API.info('error:' + e.error);
};

// open the client
xhr.open('GET', 'http://appc.mrtechnologybd.com/node.xml');

// send the data
xhr.send();

self.open();

node.xml

<?xml version="1.0" encoding="utf-8"?>
<animals>
  <animal>
    <type id="mammal">
      <kind>Dog</kind>
      <name>Duke</name>
    </type>
  </animal>
  <animal>
    <type id="Reptile">
      <kind>Frog</kind>
      <name>Kermit</name>
    </type>
  </animal>
</animals>