Code
mlDoc=loadXMLDoc("books.xml");

//the x variable will hold a node list
x=xmlDoc.getElementsByTagName('title');

for (i=0;i<x.length;i++)
{
document.write(x[i].childNodes[0].nodeValue);
document.write("<br />");
}

XmlReader
function XmlManager(){
/// <summary>
/// 管理 XmlReader 类. 使用方法参见示例代码 JsDemons/Html/XmlDemon.js.
/// 请尊重作者劳动, 引用需注明出处.
/// Howard.Queen@hotmail.com, 2008-04-24.
/// http://howard-queen.cnblogs.com/
/// 2008-07-10 
///     1, 实现了 Firefox 下的所有功能. 完美支持 Firefox.
///     2, 加入 GetSingleNode 方法, 试图提高算法效率.
/// </summary>
    if ((typeof document.implementation != 'undefined') 
    && (typeof document.implementation.createDocument != 'undefined')){
         XmlReader.prototype = {
            _Init: function(){
                this._xmlDoc = document.implementation.createDocument("", "", null);
                this._xmlDoc.async = false;
                this._domParser = new DOMParser();
                this._nsResolver = null;
            },
            GetRoot: function(name){
                return this.GetSingleNode(this._xmlDoc.documentElement, '/' + name);    
            },
            GetSingleNode: function(parentNode, targetChildName){
                return this._xmlDoc.evaluate(targetChildName, parentNode, this._nsResolver, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null).snapshotItem(0);
            },
            GetNodes: function(parentNode, targetChildName){
                var items = this._xmlDoc.evaluate(targetChildName, parentNode, this._nsResolver, 
                       XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
                var nodes = new Array();
                for( var i = 0; i < items.snapshotLength; i++){
                    nodes.push(items.snapshotItem(i));
                }
                return nodes;
            },
            GetNodeValue: function(targetNode){
                if(targetNode.childNodes.length > 0)
                    return targetNode.childNodes[0].nodeValue;
                else
                    return '';
            },
            GetAttribute: function(targetNode, attributeName){
                return targetNode.getAttribute(attributeName)
            },
            LoadXml: function(xmlText){
                var childNodes = this._xmlDoc.childNodes;
                for (var i = childNodes.length - 1; i >= 0; i--)
                    this._xmlDoc.removeChild(childNodes[i]);
                this._xmlDoc.appendChild(this._xmlDoc.importNode(this._domParser.parseFromString(xmlText, "text/xml").documentElement, true));
                this._nsResolver = this._xmlDoc.createNSResolver(this._xmlDoc.documentElement);
            },
            LoadUrl: function(url){
                this._xmlDoc.load(url);
                this._nsResolver = this._xmlDoc.createNSResolver(this._xmlDoc.documentElement);
            }
        }
    }
    else if (typeof window.ActiveXObject != 'undefined'){//IE浏览器          
         XmlReader.prototype = {
            _Init: function(){
                this._xmlDoc = new ActiveXObject("MSXML2.DOMDocument.3.0"); 
                this._xmlDoc.async = false;
                while(this._xmlDoc.readyState != 4) {
                };
            },
            GetRoot: function(name){
                return this.GetSingleNode(this._xmlDoc.documentElement, '/' + name);    
            },
            GetSingleNode: function(parentNode, targetChildName){
                return parentNode.selectSingleNode(targetChildName);
            },
            GetNodes: function(parentNode, targetChildName){
                return parentNode.selectNodes(targetChildName);
            },
            GetNodeValue: function(targetNode){
                return targetNode.text;
            },
            GetAttribute: function(targetNode, attributeName){
                return targetNode.getAttribute(attributeName)
            },
            LoadXml: function(xmlText){
                this._xmlDoc.loadXML(xmlText);
            },
            LoadUrl: function(url){
                this._xmlDoc.load(url);
            }
        }
    }
    else{
        throw {name:"ExplorerException",message:"不可识别的浏览器, 创建 XmlManager 失败."};
    }
}

function XmlReader(){
/// <summary>
/// 用于同步读取 Xml 的类. 使用方法参见示例代码 JsDemons/Html/XmlDemon.js.
/// 请尊重作者劳动, 引用需注明出处.
/// Howard.Queen@hotmail.com, 2008-04-24.
/// </summary>
    this._xmlDoc = null;//[私有]xml 文档.
    this._Init();
}

XmlReader.prototype = {
    _Init: function(){
    /// <summary>[私有]初始化.</summary>
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."};
    },
    GetRoot: function(name){
    /// <summary>获取根节点.</summary>
    /// <param name="name" type="String">根名称.</param>
    /// <returns>根节点对象.</returns>
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."};        
    },
    GetSingleNode: function(parentNode, targetChildName){
    /// <summary>获取首个子节点.</summary>
    /// <param name="parentNode" type="XmlNode">父节点.</param>
    /// <param name="targetChildName type="String">子节点名称.</param>
    /// <returns>首个子节点.</returns>
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."};     
    },
    GetNodes: function(parentNode, targetChildName){  
    /// <summary>获取子节点集合.</summary>
    /// <param name="parentNode" type="XmlNode">父节点.</param>
    /// <param name="targetChildName type="String">子节点名称.</param>
    /// <returns>子节点集合.</returns>
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."};          
    },
    GetNodeValue: function(targetNode){
    /// <summary>获取节点的内容.</summary>
    /// <param name="targetNode" type="XmlNode">目标节点.</param>
    /// <returns>节点内容.</returns>
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."};    
    },
    GetAttribute: function(targetNode, attributeName){
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."};  
    },
    LoadXml: function(xmlText){
    /// <summary>加载 xml 文本.</summary>
    /// <param name="xmlText" type="String">xml 文本.</param>
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."}; 
    },
    LoadUrl: function(url){
    /// <summary>加载 xml 文件.</summary>
    /// <param name="url" type="Uri">xml 文件 Uri.</param>
        throw {name:"",message:"请在实例化 XmlReader 前创建一个 XmlManager 实例."}; 
    }
}

Code
try{    
        //---------------------
        //配置 XmlReader 类以适应当前浏览器环境.
        var xm = new XmlManager();
        //创建 XmlReader 实例.
        var xr = new XmlReader();
        
        //自定义处理函数
        function Show(){
            //开始输出.
            var root = xr.GetRoot("Nodes");
            var nodes = xr.GetNodes(root,"Node");
            for(var i = 0;i<nodes.length;i++){
                var name = xr.GetNodes(nodes[i], "Name")[0];
                var sex = xr.GetNodes(nodes[i], "Sex")[0];
                var age = xr.GetNodes(nodes[i], "Age")[0];            
                document.write("Name: " + xr.GetNodeValue(name) + " Sex: " + xr.GetNodeValue(sex) + " Age: " + xr.GetNodeValue(age) + "<br/>");
            }
        }  
        
        //---------------------
        //应用1, 通常调用1.
        document.write("LoadXml:<br/>");
        var xml = "<?xml version=\"1.0\" encoding=\"utf-8\"?><Nodes><Node><Name>Q</Name><Sex>Boy</Sex><Age>10</Age></Node><Node><Name>I</Name><Sex>Girl</Sex><Age>11</Age></Node></Nodes>";
        xr.LoadXml(xml);
        Show();
        document.write("<br/>");
        
        document.write("ReLoadXml:<br/>");
        xr.LoadXml(xml);
        Show();
    }
    catch(e){//跟踪错误
        alert(e.name + ' ' + e.message);
    }