IE8 Shim for DOMImplementation.prototype.createDocument (does not support doctype argument nor wrap the resulting document to support all DOM methods and properties; mostly for loading XML)

DOMImplementation.prototype.createDocument.js

/*globals DOMImplementation, ActiveXObject */
if (!DOMImplementation.prototype.createDocument) {

(function () {
'use strict';

var i, docObj, docObjType,
    docObjs = [
        'MSXML6.DOMDocument', 'MSXML5.DOMDocument', 'MSXML4.DOMDocument',
        'MSXML3.DOMDocument', 'MSXML2.DOMDocument.5.0', 'MSXML2.DOMDocument.4.0',
        'MSXML2.DOMDocument.3.0', 'MSXML2.DOMDocument', 'MSXML.DomDocument',
        'Microsoft.XmlDom'
    ],
    dol = docObjs.length;

for (i=0; i < dol; i++) {
    try {
        docObj = new ActiveXObject(docObjs[i]);
        docObjType = docObjs[i]; // Set this after ActiveXObject to ensure only set if no errors thrown
        break;
    }
    catch (e) {
    }
}

/**
* This shim implementation does not provide any support for doctype, nor does it wrap the resulting
* document so as to support all current DOM methods and properties
*/
DOMImplementation.prototype.createDocument = function (namespace, qualifiedName, doctype) {
    if (doctype) {
        throw 'This is not a complete shim for ' +
                        'DOMImplementation.prototype.createDocument.';
    }
    if (!docObjType) {
        throw 'Could not create a DOM document object';
    }
    var pos, prefix, 
        prefixedNs = '',
        doc = new ActiveXObject(docObjType);

    if (qualifiedName) {
         pos = qualifiedName.indexOf(':');
        if (pos > -1) {
            prefix = qualifiedName.slice(0, pos);
            prefixedNs = ' xmlns:' + prefix + '="' + namespace + '"';
        }
        else if (namespace) {
            prefixedNs = ' xmlns="' + namespace + '"';
        }
        doc.loadXML('<' + qualifiedName + prefixedNs + '/>');
    }
    return doc;
};

}());

}