访问XML-01-创建文档对象

function XmlDocument() {}
XmlDocument.create = function () {
    if (document.implementation && document.implementation.createDocument) {
          return document.implementation.createDocument("", "", null);
    } else if (window.ActiveXObject) {
        try {
            var prefix = ["MSXML2", "MSXML", "Microsoft", "MSXML3"];
            for (var i = 0; i < prefix.length; i++) {
                 var obj = new ActiveXObject(prefix[i] + ".DomDocument");
                 if (obj == null || typeof(obj) == 'undefined') {
                      continue;
                 } else {
                      return obj;
                 }
             }
          } catch (e) {
                   //^_^
                   throw new Error("My God, What version of IE are you using? IE5&+ is requiered.");
          }
     } else
           throw new Error("Cannot create DOM Document!");
}