xml解析兼容ie8以及以下

ie9,10下虽然报了new window.DOMParser()不兼容的错误，但是其实执行没问题的，如果项目要求兼容到ie8，如下写法：

// 解析xml兼容

    function parseXml(xmlStr) {
        var obj, xmlDoc;
        if (typeof window.DOMParser != "undefined") {
            obj = function (xmlStr) {
                return ( new window.DOMParser() ).parseFromString(xmlStr, "text/xml");
            };
        } else if (typeof window.ActiveXObject != "undefined" && new window.ActiveXObject("Microsoft.XMLDOM")) {
            obj = function (xmlStr) {
                xmlDoc = new window.ActiveXObject("Microsoft.XMLDOM");
                xmlDoc.async = "false";
                xmlDoc.loadXML(xmlStr);
                return xmlDoc;
            };

        } else {
            throw new Error("No XML parser found");
        }
        return obj(xmlStr);
    }


    var str = "<wrapper><success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/></wrapper>";
    var xml = parseXml(str);
    console.log(xml);
    console.log(xml.documentElement.nodeName);