我所认识的XPath

<?xml version="1.0" encoding="iso-8859-1"?>
<bookstore>
  <book category="COOKING">
    <title lang="en">Everyday Italian</title>
    <author>Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>
  <book category="CHILDREN">
    <title lang="en">Harry Potter</title>
    <author>J K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="WEB">
    <title lang="en">XQuery Kick Start</title>
    <author>James McGovern</author>
    <author>Per Bothner</author>
    <author>Kurt Cagle</author>
    <author>James Linn</author>
    <author>Vaidyanathan Nagarajan</author>
    <year>2003</year>
    <price>49.99</price>
  </book>
  <book category="WEB">
    <title lang="en">Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>
</bookstore>

    <div id="divResult">这是答案区域</div>
    <hr />
    <input id="txt" type="text" value="/bookstore/book/title" />
    <input id="btn" type="button" value="获得结果" />

        /*
        *@desc:加载xml文件
        */
        function loadXMLDoc(path) {
            if (window.XMLHttpRequest) {// code for IE
                xhttp = new XMLHttpRequest();
            }
            else {// code for Mozilla, Firefox, Opera, etc.
                xhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            xhttp.open("GET", path, false);
            xhttp.send("");
            return xhttp.responseXML;//返回xml结果
        }


        /*
        *@desc:通过xpath路径来获得相应的xml结果
        */
        function getXmlResultByPath(path) {
            var xml = loadXMLDoc("books.xml"),
                arrResult = [];

            // code for IE
            if (window.ActiveXObject) {
                var nodes = xml.selectNodes(path);
                for (i = 0; i < nodes.length; i++) {
                    if (nodes[i].childNodes[0] == undefined) {
                        arrResult.push(nodes[i].childNodes[0].nodeValue);
                    } else {
                        arrResult.push(nodes[i].nodeValue);
                    }
                }
            }
                // code for Mozilla, Firefox, Opera, etc.
            else if (document.implementation && document.implementation.createDocument) {
                var nodes = xml.evaluate(path, xml, null, XPathResult.ANY_TYPE, null);
                var result = nodes.iterateNext();
                while (result) {
                    if (result.childNodes[0] == undefined) {
                        arrResult.push(result.nodeValue);
                    } else {
                        arrResult.push(result.childNodes[0].nodeValue);
                    }
                    result = nodes.iterateNext();
                }
            }
            return arrResult.join(‘,‘);//结果以逗号分隔
        }


        window.onload = function () {
            btn.onclick = function () {
                divResult.innerHTML = getXmlResultByPath(document.getElementById(‘txt‘).value);
            }
        }

<bookstore> （文档节点）
<author>J K. Rowling</author> （元素节点）
lang="en" （属性节点）