In general, parsing XML requires a great deal of effort on the part of the JavaScript programmer. Aside from knowing the particulars of the structure ahead of time, you must also know exactly how to pull apart that structure and painstakingly reassemble it into a JavaScript object.

parseXML.js

var users = [];
 var userNodes = responseXML.getElementsByTagName('users');
 var node, usernameNodes, usernameNode, username,
 realnameNodes, realnameNode, realname,
 emailNodes, emailNode, email;
 for (var i = 0, len = userNodes.length; i < len; i++) {
 node = userNodes[i];
 username = realname = email = '';
 usernameNodes = node.getElementsByTagName('username');
 if (usernameNodes && usernameNodes[0]) {
 usernameNode = usernameNodes[0];
 username = (usernameNodes.firstChild) ?
 usernameNodes.firstChild.nodeValue : '';
 }
 realnameNodes = node.getElementsByTagName('realname');
 if (realnameNodes && realnameNodes[0]) {
 realnameNode = realnameNodes[0];
 realname = (realnameNodes.firstChild) ?
 realnameNodes.firstChild.nodeValue : '';
 }
 emailNodes = node.getElementsByTagName('email');
if (emailNodes && emailNodes[0]) {
 emailNode = emailNodes[0];
 email = (emailNodes.firstChild) ?
 emailNodes.firstChild.nodeValue : '';
 }
 users[i] = {
 id: node.getAttribute('id'),
 username: username,
 realname: realname,
 email: email
 };
 }
 return users;
}