WebWorkerFakeDOM.js

var document = self.document = { parentNode: null, nodeType: 9, toString: function () { return "FakeDocument" } };
var window = self.window = self;
var fakeElement = Object.create(document);
fakeElement.nodeType = 1;
fakeElement.toString = function () { return "FakeElement" };
fakeElement.parentNode = fakeElement.firstChild = fakeElement.lastChild = fakeElement;
fakeElement.ownerDocument = document;

document.head = document.body = fakeElement;
document.ownerDocument = document.documentElement = document;
document.getElementById = document.createElement = function () { return fakeElement; };
document.createDocumentFragment = function () { return this; };
document.getElementsByTagName = document.getElementsByClassName = function () { return [fakeElement]; };
document.getAttribute = document.setAttribute = document.removeChild =
    document.addEventListener = document.removeEventListener =
    function () { return null; };
document.cloneNode = document.appendChild = function () { return this; };
document.appendChild = function (child) { return child; };
document.childNodes = [];
document.implementation = {
    createHTMLDocument: function () { return document; }
}