JAVASCRIPT LIbrary for E4X - Greasemonkey script

// ==UserScript==
// @name        JAVASCRIPT LIbrary for E4X
// @namespace   decembre
// @include     *
// @version     1
// @grant       none
// ==/UserScript==
/*
 * e4x.js
 *
 * A JavaScript library that implements the optional E4X features described in
 * ECMA-357 2nd Edition Annex A if they are not already implemented.
 *
 * 2010-06-30
 *
 * By Eli Grey, http://eligrey.com
 * License: The X11/MIT license (see LICENSE.md)
 */

/*global document, XML, XMLList, XMLSerializer, XPathResult */

/*jslint undef: true, nomen: true, eqeqeq: true, bitwise: true, regexp: true,
  newcap: true, immed: true, maxerr: 1000, maxlen: 90 */

 // Solution given by Paul Sweatte (StackOverflow):
 //<a href="http://stackoverflow.com/users/1113772/paul-sweatte">Paul Sweatte</a>
 //In <a href="http://stackoverflow.com/questions/17651655/convert-a-greasemonkey-script-after-e4x-is-not-supported">How to convert this script which use deprecadted E4X ? :</a>

  //The JavaScript implementation uses XMLSerializer, which is unsafe in Greasemonkey.
  //As a workaround, copy and paste the code into your script,
  //then replace XMLSerializer with unsafeWindow.XMLSerializer to access that API via the target page.
  //Be aware that it is possible for scripts on the target page to follow unsafeWindow usage back to the Greasemonkey script reference and thus gain elevated privileges

/*! @source http://purl.eligrey.com/github/e4x.js/blob/master/e4x.js*/

"use strict";

(function (XML) {
    var hostDoc   = document,
    unsafeWindow.XMLSerializer = new unsafeWindow.XMLSerializer,
    piName        = /^[\w\-]+\s*/,
    NULL          = null,
    createDoc     = function (docElem) {
        var domDoc = hostDoc.implementation.createDocument(NULL, NULL, NULL);
        if (docElem) {
            domDoc.appendChild(docElem);
        }
        return domDoc;
    },
    xmlDoc        = createDoc(),

    xmlToDomNode = function (xml) {
        var node;

        switch (xml.nodeKind()) {
            case "element":
                var attributes = xml.attributes(),
                    children   = xml.children(),
                    childLen   = children.length(),
                    attLen     = attributes.length(),
                    i, attribute;

                node = xmlDoc.createElementNS(
                    xml.namespace().uri,
                    xml.localName()
                );

                if (attLen !== 0) {
                    for (i = 0; i < attLen; i++) {
                        attribute = attributes[i];
                        node.setAttributeNS(
                            attribute.namespace().uri,
                            attribute.localName(),
                            attribute.toString()
                        );
                    }
                }
                if (childLen !== 0) {
                    for (i = 0; i < childLen; i++) {
                        node.appendChild(xmlToDomNode(children[i]));
                    }
                }

                return node;

            case "text":
                return xmlDoc.createTextNode(xml.toString());

            case "comment":
                return xmlDoc.createComment(xml.toString().slice(4, -3));

            case "processing-instruction":
                return xmlDoc.createProcessingInstruction(
                    xml.localName(),
                    xml.toString().slice(2, -2).replace(piName, "")
                );

            case "attribute":
                (node = xmlDoc.createAttributeNS(
                    xml.namespace().uri,
                    xml.localName()
                )).nodeValue = xml.toString();
                return node;
        }
    },
    xmlMethods = {
        domNode: function () {
            if (this.length() === 1) {
                return hostDoc.adoptNode(xmlToDomNode(this));
            }
        },
        domNodeList: function () {
            var fragment = hostDoc.createDocumentFragment();

            for (var i = 0, len = this.length(); i < len; i++) {
                fragment.appendChild(this[i].domNode());
            }

            return hostDoc.adoptNode(fragment).childNodes;
        },
        xpath: function (xpathExp) {
            var res = new XMLList,
                len = this.length();

            if (len !== 1) {
                for (var i = 0, len = len; i < len; i++) {
                    res += this[i].xpath(xpathExp);
                }
                return res;
            }

            var domDoc = createDoc(this.domNode()),
            xpr = domDoc.evaluate(
                xpathExp,
                domDoc.documentElement,
                domDoc.createNSResolver(domDoc.documentElement),
                XPathResult.ORDERED_NODE_ITERATOR_TYPE,
                NULL
            ),
            node;

            while (node = xpr.iterateNext()) {
                // Unfortunately, there's no efficient native XML.fromDomNode(node) method
                res += new XML(unsafeWindow.XMLSerializer.serializeToString(node));
            }

            return res;
        }
    },
    method;

    for (method in xmlMethods) {
        if (xmlMethods.hasOwnProperty(method) && !XML.prototype.function::[method]) {
            XML.prototype.function::[method] = xmlMethods[method];
        }
    }
}(XML));