lib/jsdom/browser/Window.js
function Window(options) {
  EventTarget.setup(this);

  const rawPerformance = new RawPerformance();
  const windowInitialized = rawPerformance.now();

  const window = this;

  mixin(window, WindowEventHandlersImpl.prototype);
  mixin(window, GlobalEventHandlersImpl.prototype);

  this._initGlobalEvents();

  ///// INTERFACES FROM THE DOM
  // TODO: consider a mode of some sort where these are not shared between all DOM instances
  // It'd be very memory-expensive in most cases, though.
  for (const name in dom) {
    Object.defineProperty(window, name, {
      enumerable: false,
      configurable: true,
      writable: true,
      value: dom[name]
    });
  }

  ///// PRIVATE DATA PROPERTIES

  this._resourceLoader = options.resourceLoader;

  // vm initialization is deferred until script processing is activated
  this._globalProxy = this;
  Object.defineProperty(idlUtils.implForWrapper(this), idlUtils.wrapperSymbol, { get: () => this._globalProxy });

  let timers = Object.create(null);
  let animationFrameCallbacks = Object.create(null);

  // List options explicitly to be clear which are passed through
  this._document = Document.create([], {
    options: {
      parsingMode: options.parsingMode,
      contentType: options.contentType,
      encoding: options.encoding,
      cookieJar: options.cookieJar,
      url: options.url,
      lastModified: options.lastModified,
      referrer: options.referrer,
      concurrentNodeIterators: options.concurrentNodeIterators,
      parseOptions: options.parseOptions,
      defaultView: this._globalProxy,
      global: this
    }
  });
  // https://html.spec.whatwg.org/#session-history
  this._sessionHistory = new SessionHistory({
    document: idlUtils.implForWrapper(this._document),
    url: idlUtils.implForWrapper(this._document)._URL,
    stateObject: null
  }, this);

  this._virtualConsole = options.virtualConsole;

  this._runScripts = options.runScripts;
  if (this._runScripts === "outside-only" || this._runScripts === "dangerously") {
    contextifyWindow(this);
  }

  // Set up the window as if it's a top level window.
  // If it's not, then references will be corrected by frame/iframe code.
  this._parent = this._top = this._globalProxy;
  this._frameElement = null;

  // This implements window.frames.length, since window.frames returns a
  // self reference to the window object.  This value is incremented in the
  // HTMLFrameElement implementation.
  this._length = 0;

  this._pretendToBeVisual = options.pretendToBeVisual;
  this._storageQuota = options.storageQuota;

  // Some properties (such as localStorage and sessionStorage) share data
  // between windows in the same origin. This object is intended
  // to contain such data.
  if (options.commonForOrigin && options.commonForOrigin[this._document.origin]) {
    this._commonForOrigin = options.commonForOrigin;
  } else {
    this._commonForOrigin = {
      [this._document.origin]: {
        localStorageArea: new Map(),
        sessionStorageArea: new Map(),
        windowsInSameOrigin: [this]
      }
    };
  }

  this._currentOriginData = this._commonForOrigin[this._document.origin];

  ///// WEB STORAGE

  this._localStorage = Storage.create([], {
    associatedWindow: this,
    storageArea: this._currentOriginData.localStorageArea,
    type: "localStorage",
    url: this._document.documentURI,
    storageQuota: this._storageQuota
  });
  this._sessionStorage = Storage.create([], {
    associatedWindow: this,
    storageArea: this._currentOriginData.sessionStorageArea,
    type: "sessionStorage",
    url: this._document.documentURI,
    storageQuota: this._storageQuota
  });

  ///// GETTERS

  const locationbar = BarProp.create();
  const menubar = BarProp.create();
  const personalbar = BarProp.create();
  const scrollbars = BarProp.create();
  const statusbar = BarProp.create();
  const toolbar = BarProp.create();
  const external = External.create();
  const navigator = Navigator.create([], { userAgent: this._resourceLoader._userAgent });
  const performance = Performance.create([], { rawPerformance });
  const screen = Screen.create();

  define(this, {
    get length() {
      return window._length;
    },
    get window() {
      return window._globalProxy;
    },
    get frameElement() {
      return idlUtils.wrapperForImpl(window._frameElement);
    },
    get frames() {
      return window._globalProxy;
    },
    get self() {
      return window._globalProxy;
    },
    get parent() {
      return window._parent;
    },
    get top() {
      return window._top;
    },
    get document() {
      return window._document;
    },
    get external() {
      return external;
    },
    get location() {
      return idlUtils.wrapperForImpl(idlUtils.implForWrapper(window._document)._location);
    },
    get history() {
      return idlUtils.wrapperForImpl(idlUtils.implForWrapper(window._document)._history);
    },
    get navigator() {
      return navigator;
    },
    get locationbar() {
      return locationbar;
    },
    get menubar() {
      return menubar;
    },
    get personalbar() {
      return personalbar;
    },
    get scrollbars() {
      return scrollbars;
    },
    get statusbar() {
      return statusbar;
    },
    get toolbar() {
      return toolbar;
    },
    get performance() {
      return performance;
    },
    get screen() {
      return screen;
    },
    get localStorage() {
      if (this._document.origin === "null") {
        throw new DOMException("localStorage is not available for opaque origins", "SecurityError");
      }

      return this._localStorage;
    },
    get sessionStorage() {
      if (this._document.origin === "null") {
        throw new DOMException("sessionStorage is not available for opaque origins", "SecurityError");
      }

      return this._sessionStorage;
    }
  });

  namedPropertiesWindow.initializeWindow(this, this._globalProxy);

  ///// METHODS for [ImplicitThis] hack
  // See https://lists.w3.org/Archives/Public/public-script-coord/2015JanMar/0109.html
  this.addEventListener = this.addEventListener.bind(this);
  this.removeEventListener = this.removeEventListener.bind(this);
  this.dispatchEvent = this.dispatchEvent.bind(this);

  ///// METHODS

  let latestTimerId = 0;
  let latestAnimationFrameCallbackId = 0;

  this.setTimeout = function (fn, ms) {
    const args = [];
    for (let i = 2; i < arguments.length; ++i) {
      args[i - 2] = arguments[i];
    }
    return startTimer(window, setTimeout, clearTimeout, ++latestTimerId, fn, ms, timers, args);
  };
  this.setInterval = function (fn, ms) {
    const args = [];
    for (let i = 2; i < arguments.length; ++i) {
      args[i - 2] = arguments[i];
    }
    return startTimer(window, setInterval, clearInterval, ++latestTimerId, fn, ms, timers, args);
  };
  this.clearInterval = stopTimer.bind(this, timers);
  this.clearTimeout = stopTimer.bind(this, timers);

  if (this._pretendToBeVisual) {
    this.requestAnimationFrame = fn => {
      const timestamp = rawPerformance.now() - windowInitialized;
      const fps = 1000 / 60;

      return startTimer(
        window,
        setTimeout,
        clearTimeout,
        ++latestAnimationFrameCallbackId,
        fn,
        fps,
        animationFrameCallbacks,
        [timestamp]
      );
    };
    this.cancelAnimationFrame = stopTimer.bind(this, animationFrameCallbacks);
  }

  this.__stopAllTimers = function () {
    stopAllTimers(timers);
    stopAllTimers(animationFrameCallbacks);

    latestTimerId = 0;
    latestAnimationFrameCallbackId = 0;

    timers = Object.create(null);
    animationFrameCallbacks = Object.create(null);
  };

  function Option(text, value, defaultSelected, selected) {
    if (text === undefined) {
      text = "";
    }
    text = webIDLConversions.DOMString(text);

    if (value !== undefined) {
      value = webIDLConversions.DOMString(value);
    }

    defaultSelected = webIDLConversions.boolean(defaultSelected);
    selected = webIDLConversions.boolean(selected);

    const option = window._document.createElement("option");
    const impl = idlUtils.implForWrapper(option);

    if (text !== "") {
      impl.text = text;
    }
    if (value !== undefined) {
      impl.setAttributeNS(null, "value", value);
    }
    if (defaultSelected) {
      impl.setAttributeNS(null, "selected", "");
    }
    impl._selectedness = selected;

    return option;
  }
  Object.defineProperty(Option, "prototype", {
    value: this.HTMLOptionElement.prototype,
    configurable: false,
    enumerable: false,
    writable: false
  });
  Object.defineProperty(window, "Option", {
    value: Option,
    configurable: true,
    enumerable: false,
    writable: true
  });

  function Image() {
    const img = window._document.createElement("img");
    const impl = idlUtils.implForWrapper(img);

    if (arguments.length > 0) {
      impl.setAttributeNS(null, "width", String(arguments[0]));
    }
    if (arguments.length > 1) {
      impl.setAttributeNS(null, "height", String(arguments[1]));
    }

    return img;
  }
  Object.defineProperty(Image, "prototype", {
    value: this.HTMLImageElement.prototype,
    configurable: false,
    enumerable: false,
    writable: false
  });
  Object.defineProperty(window, "Image", {
    value: Image,
    configurable: true,
    enumerable: false,
    writable: true
  });

  function Audio(src) {
    const audio = window._document.createElement("audio");
    const impl = idlUtils.implForWrapper(audio);
    impl.setAttributeNS(null, "preload", "auto");

    if (src !== undefined) {
      impl.setAttributeNS(null, "src", String(src));
    }

    return audio;
  }
  Object.defineProperty(Audio, "prototype", {
    value: this.HTMLAudioElement.prototype,
    configurable: false,
    enumerable: false,
    writable: false
  });
  Object.defineProperty(window, "Audio", {
    value: Audio,
    configurable: true,
    enumerable: false,
    writable: true
  });

  this.postMessage = postMessage;

  this.atob = function (str) {
    const result = atob(str);
    if (result === null) {
      throw new DOMException("The string to be decoded contains invalid characters.", "InvalidCharacterError");
    }
    return result;
  };

  this.btoa = function (str) {
    const result = btoa(str);
    if (result === null) {
      throw new DOMException("The string to be encoded contains invalid characters.", "InvalidCharacterError");
    }
    return result;
  };

  this.FileReader = createFileReader({
    window: this
  }).interface;
  this.WebSocket = createWebSocket({
    window: this
  }).interface;

  const AbortSignalWrapper = createAbortSignal({
    window: this
  });
  this.AbortSignal = AbortSignalWrapper.interface;
  this.AbortController = createAbortController({
    AbortSignal: AbortSignalWrapper
  }).interface;

  this.XMLHttpRequest = createXMLHttpRequest(this);

  // TODO: necessary for Blob and FileReader due to different-globals weirdness; investigate how to avoid this.
  this.ArrayBuffer = ArrayBuffer;
  this.Int8Array = Int8Array;
  this.Uint8Array = Uint8Array;
  this.Uint8ClampedArray = Uint8ClampedArray;
  this.Int16Array = Int16Array;
  this.Uint16Array = Uint16Array;
  this.Int32Array = Int32Array;
  this.Uint32Array = Uint32Array;
  this.Float32Array = Float32Array;
  this.Float64Array = Float64Array;

  this.stop = function () {
    const manager = idlUtils.implForWrapper(this._document)._requestManager;
    if (manager) {
      manager.close();
    }
  };

  this.close = function () {
    // Recursively close child frame windows, then ourselves.
    const currentWindow = this;
    (function windowCleaner(windowToClean) {
      for (let i = 0; i < windowToClean.length; i++) {
        windowCleaner(windowToClean[i]);
      }

      // We"re already in our own window.close().
      if (windowToClean !== currentWindow) {
        windowToClean.close();
      }
    }(this));

    // Clear out all listeners. Any in-flight or upcoming events should not get delivered.
    idlUtils.implForWrapper(this)._eventListeners = Object.create(null);

    if (this._document) {
      if (this._document.body) {
        this._document.body.innerHTML = "";
      }

      if (this._document.close) {
        // It's especially important to clear out the listeners here because document.close() causes a "load" event to
        // fire.
        idlUtils.implForWrapper(this._document)._eventListeners = Object.create(null);
        this._document.close();
      }
      const doc = idlUtils.implForWrapper(this._document);
      if (doc._requestManager) {
        doc._requestManager.close();
      }
      delete this._document;
    }

    this.__stopAllTimers();
    WebSocketImpl.cleanUpWindow(this);
  };

  this.getComputedStyle = function (elt) {
    elt = Element.convert(elt);

    const declaration = new CSSStyleDeclaration();
    const { forEach, indexOf } = Array.prototype;
    const { style } = elt;

    function setPropertiesFromRule(rule) {
      if (!rule.selectorText) {
        return;
      }

      const cssSelectorSplitRe = /((?:[^,"']|"[^"]*"|'[^']*')+)/;
      const selectors = rule.selectorText.split(cssSelectorSplitRe);
      let matched = false;

      for (const selectorText of selectors) {
        if (selectorText !== "" && selectorText !== "," && !matched && matchesDontThrow(elt, selectorText)) {
          matched = true;
          forEach.call(rule.style, property => {
            declaration.setProperty(
              property,
              rule.style.getPropertyValue(property),
              rule.style.getPropertyPriority(property)
            );
          });
        }
      }
    }

    function readStylesFromStyleSheet(sheet) {
      forEach.call(sheet.cssRules, rule => {
        if (rule.media) {
          if (indexOf.call(rule.media, "screen") !== -1) {
            forEach.call(rule.cssRules, setPropertiesFromRule);
          }
        } else {
          setPropertiesFromRule(rule);
        }
      });
    }

    if (!parsedDefaultStyleSheet) {
      parsedDefaultStyleSheet = cssom.parse(defaultStyleSheet);
    }
    readStylesFromStyleSheet(parsedDefaultStyleSheet);
    forEach.call(elt.ownerDocument.styleSheets, readStylesFromStyleSheet);

    forEach.call(style, property => {
      declaration.setProperty(property, style.getPropertyValue(property), style.getPropertyPriority(property));
    });

    return declaration;
  };

  // The captureEvents() and releaseEvents() methods must do nothing
  this.captureEvents = function () {};

  this.releaseEvents = function () {};

  ///// PUBLIC DATA PROPERTIES (TODO: should be getters)

  function wrapConsoleMethod(method) {
    return (...args) => {
      window._virtualConsole.emit(method, ...args);
    };
  }

  this.console = {
    assert: wrapConsoleMethod("assert"),
    clear: wrapConsoleMethod("clear"),
    count: wrapConsoleMethod("count"),
    countReset: wrapConsoleMethod("countReset"),
    debug: wrapConsoleMethod("debug"),
    dir: wrapConsoleMethod("dir"),
    dirxml: wrapConsoleMethod("dirxml"),
    error: wrapConsoleMethod("error"),
    group: wrapConsoleMethod("group"),
    groupCollapsed: wrapConsoleMethod("groupCollapsed"),
    groupEnd: wrapConsoleMethod("groupEnd"),
    info: wrapConsoleMethod("info"),
    log: wrapConsoleMethod("log"),
    table: wrapConsoleMethod("table"),
    time: wrapConsoleMethod("time"),
    timeEnd: wrapConsoleMethod("timeEnd"),
    trace: wrapConsoleMethod("trace"),
    warn: wrapConsoleMethod("warn")
  };

  function notImplementedMethod(name) {
    return function () {
      notImplemented(name, window);
    };
  }

  define(this, {
    name: "",
    status: "",
    devicePixelRatio: 1,
    innerWidth: 1024,
    innerHeight: 768,
    outerWidth: 1024,
    outerHeight: 768,
    pageXOffset: 0,
    pageYOffset: 0,
    screenX: 0,
    screenLeft: 0,
    screenY: 0,
    screenTop: 0,
    scrollX: 0,
    scrollY: 0,

    alert: notImplementedMethod("window.alert"),
    blur: notImplementedMethod("window.blur"),
    confirm: notImplementedMethod("window.confirm"),
    focus: notImplementedMethod("window.focus"),
    moveBy: notImplementedMethod("window.moveBy"),
    moveTo: notImplementedMethod("window.moveTo"),
    open: notImplementedMethod("window.open"),
    print: notImplementedMethod("window.print"),
    prompt: notImplementedMethod("window.prompt"),
    resizeBy: notImplementedMethod("window.resizeBy"),
    resizeTo: notImplementedMethod("window.resizeTo"),
    scroll: notImplementedMethod("window.scroll"),
    scrollBy: notImplementedMethod("window.scrollBy"),
    scrollTo: notImplementedMethod("window.scrollTo")
  });

  ///// INITIALIZATION

  process.nextTick(() => {
    if (!window.document) {
      return; // window might've been closed already
    }

    if (window.document.readyState === "complete") {
      fireAnEvent("load", window, undefined, {}, window.document);
    } else {
      window.document.addEventListener("load", () => {
        fireAnEvent("load", window, undefined, {}, window.document);

        if (!idlUtils.implForWrapper(window._document)._pageShowingFlag) {
          idlUtils.implForWrapper(window._document)._pageShowingFlag = true;
          fireAnEvent("pageshow", window, PageTransitionEvent, { persisted: false }, window.document);
        }
      });
    }
  });
}
function Window(options) {
  EventTarget.setup(this);

  const rawPerformance = new RawPerformance();
  const windowInitialized = rawPerformance.now();

  const window = this;

  mixin(window, WindowEventHandlersImpl.prototype);
  mixin(window, GlobalEventHandlersImpl.prototype);

  this._initGlobalEvents();

  ///// INTERFACES FROM THE DOM
  // TODO: consider a mode of some sort where these are not shared between all DOM instances
  // It'd be very memory-expensive in most cases, though.
  for (const name in dom) {
    Object.defineProperty(window, name, {
      enumerable: false,
      configurable: true,
      writable: true,
      value: dom[name]
    });
  }

  ///// PRIVATE DATA PROPERTIES

  this._resourceLoader = options.resourceLoader;

  // vm initialization is deferred until script processing is activated
  this._globalProxy = this;
  Object.defineProperty(idlUtils.implForWrapper(this), idlUtils.wrapperSymbol, { get: () => this._globalProxy });

  let timers = Object.create(null);
  let animationFrameCallbacks = Object.create(null);

  // List options explicitly to be clear which are passed through
  this._document = Document.create([], {
    options: {
      parsingMode: options.parsingMode,
      contentType: options.contentType,
      encoding: options.encoding,
      cookieJar: options.cookieJar,
      url: options.url,
      lastModified: options.lastModified,
      referrer: options.referrer,
      concurrentNodeIterators: options.concurrentNodeIterators,
      parseOptions: options.parseOptions,
      defaultView: this._globalProxy,
      global: this
    }
  });
  // https://html.spec.whatwg.org/#session-history
  this._sessionHistory = new SessionHistory({
    document: idlUtils.implForWrapper(this._document),
    url: idlUtils.implForWrapper(this._document)._URL,
    stateObject: null
  }, this);

  this._virtualConsole = options.virtualConsole;

  this._runScripts = options.runScripts;
  if (this._runScripts === "outside-only" || this._runScripts === "dangerously") {
    contextifyWindow(this);
  }

  // Set up the window as if it's a top level window.
  // If it's not, then references will be corrected by frame/iframe code.
  this._parent = this._top = this._globalProxy;
  this._frameElement = null;

  // This implements window.frames.length, since window.frames returns a
  // self reference to the window object.  This value is incremented in the
  // HTMLFrameElement implementation.
  this._length = 0;

  this._pretendToBeVisual = options.pretendToBeVisual;
  this._storageQuota = options.storageQuota;

  // Some properties (such as localStorage and sessionStorage) share data
  // between windows in the same origin. This object is intended
  // to contain such data.
  if (options.commonForOrigin && options.commonForOrigin[this._document.origin]) {
    this._commonForOrigin = options.commonForOrigin;
  } else {
    this._commonForOrigin = {
      [this._document.origin]: {
        localStorageArea: new Map(),
        sessionStorageArea: new Map(),
        windowsInSameOrigin: [this]
      }
    };
  }

  this._currentOriginData = this._commonForOrigin[this._document.origin];

  ///// WEB STORAGE

  this._localStorage = Storage.create([], {
    associatedWindow: this,
    storageArea: this._currentOriginData.localStorageArea,
    type: "localStorage",
    url: this._document.documentURI,
    storageQuota: this._storageQuota
  });
  this._sessionStorage = Storage.create([], {
    associatedWindow: this,
    storageArea: this._currentOriginData.sessionStorageArea,
    type: "sessionStorage",
    url: this._document.documentURI,
    storageQuota: this._storageQuota
  });

  ///// GETTERS

  const locationbar = BarProp.create();
  const menubar = BarProp.create();
  const personalbar = BarProp.create();
  const scrollbars = BarProp.create();
  const statusbar = BarProp.create();
  const toolbar = BarProp.create();
  const external = External.create();
  const navigator = Navigator.create([], { userAgent: this._resourceLoader._userAgent });
  const performance = Performance.create([], { rawPerformance });
  const screen = Screen.create();

  define(this, {
    get length() {
      return window._length;
    },
    get window() {
      return window._globalProxy;
    },
    get frameElement() {
      return idlUtils.wrapperForImpl(window._frameElement);
    },
    get frames() {
      return window._globalProxy;
    },
    get self() {
      return window._globalProxy;
    },
    get parent() {
      return window._parent;
    },
    get top() {
      return window._top;
    },
    get document() {
      return window._document;
    },
    get external() {
      return external;
    },
    get location() {
      return idlUtils.wrapperForImpl(idlUtils.implForWrapper(window._document)._location);
    },
    get history() {
      return idlUtils.wrapperForImpl(idlUtils.implForWrapper(window._document)._history);
    },
    get navigator() {
      return navigator;
    },
    get locationbar() {
      return locationbar;
    },
    get menubar() {
      return menubar;
    },
    get personalbar() {
      return personalbar;
    },
    get scrollbars() {
      return scrollbars;
    },
    get statusbar() {
      return statusbar;
    },
    get toolbar() {
      return toolbar;
    },
    get performance() {
      return performance;
    },
    get screen() {
      return screen;
    },
    get localStorage() {
      if (this._document.origin === "null") {
        throw new DOMException("localStorage is not available for opaque origins", "SecurityError");
      }

      return this._localStorage;
    },
    get sessionStorage() {
      if (this._document.origin === "null") {
        throw new DOMException("sessionStorage is not available for opaque origins", "SecurityError");
      }

      return this._sessionStorage;
    }
  });

  namedPropertiesWindow.initializeWindow(this, this._globalProxy);

  ///// METHODS for [ImplicitThis] hack
  // See https://lists.w3.org/Archives/Public/public-script-coord/2015JanMar/0109.html
  this.addEventListener = this.addEventListener.bind(this);
  this.removeEventListener = this.removeEventListener.bind(this);
  this.dispatchEvent = this.dispatchEvent.bind(this);

  ///// METHODS

  let latestTimerId = 0;
  let latestAnimationFrameCallbackId = 0;

  this.setTimeout = function (fn, ms) {
    const args = [];
    for (let i = 2; i < arguments.length; ++i) {
      args[i - 2] = arguments[i];
    }
    return startTimer(window, setTimeout, clearTimeout, ++latestTimerId, fn, ms, timers, args);
  };
  this.setInterval = function (fn, ms) {
    const args = [];
    for (let i = 2; i < arguments.length; ++i) {
      args[i - 2] = arguments[i];
    }
    return startTimer(window, setInterval, clearInterval, ++latestTimerId, fn, ms, timers, args);
  };
  this.clearInterval = stopTimer.bind(this, timers);
  this.clearTimeout = stopTimer.bind(this, timers);

  if (this._pretendToBeVisual) {
    this.requestAnimationFrame = fn => {
      const timestamp = rawPerformance.now() - windowInitialized;
      const fps = 1000 / 60;

      return startTimer(
        window,
        setTimeout,
        clearTimeout,
        ++latestAnimationFrameCallbackId,
        fn,
        fps,
        animationFrameCallbacks,
        [timestamp]
      );
    };
    this.cancelAnimationFrame = stopTimer.bind(this, animationFrameCallbacks);
  }

  this.__stopAllTimers = function () {
    stopAllTimers(timers);
    stopAllTimers(animationFrameCallbacks);

    latestTimerId = 0;
    latestAnimationFrameCallbackId = 0;

    timers = Object.create(null);
    animationFrameCallbacks = Object.create(null);
  };

  function Option(text, value, defaultSelected, selected) {
    if (text === undefined) {
      text = "";
    }
    text = webIDLConversions.DOMString(text);

    if (value !== undefined) {
      value = webIDLConversions.DOMString(value);
    }

    defaultSelected = webIDLConversions.boolean(defaultSelected);
    selected = webIDLConversions.boolean(selected);

    const option = window._document.createElement("option");
    const impl = idlUtils.implForWrapper(option);

    if (text !== "") {
      impl.text = text;
    }
    if (value !== undefined) {
      impl.setAttributeNS(null, "value", value);
    }
    if (defaultSelected) {
      impl.setAttributeNS(null, "selected", "");
    }
    impl._selectedness = selected;

    return option;
  }
  Object.defineProperty(Option, "prototype", {
    value: this.HTMLOptionElement.prototype,
    configurable: false,
    enumerable: false,
    writable: false
  });
  Object.defineProperty(window, "Option", {
    value: Option,
    configurable: true,
    enumerable: false,
    writable: true
  });

  function Image() {
    const img = window._document.createElement("img");
    const impl = idlUtils.implForWrapper(img);

    if (arguments.length > 0) {
      impl.setAttributeNS(null, "width", String(arguments[0]));
    }
    if (arguments.length > 1) {
      impl.setAttributeNS(null, "height", String(arguments[1]));
    }

    return img;
  }
  Object.defineProperty(Image, "prototype", {
    value: this.HTMLImageElement.prototype,
    configurable: false,
    enumerable: false,
    writable: false
  });
  Object.defineProperty(window, "Image", {
    value: Image,
    configurable: true,
    enumerable: false,
    writable: true
  });

  function Audio(src) {
    const audio = window._document.createElement("audio");
    const impl = idlUtils.implForWrapper(audio);
    impl.setAttributeNS(null, "preload", "auto");

    if (src !== undefined) {
      impl.setAttributeNS(null, "src", String(src));
    }

    return audio;
  }
  Object.defineProperty(Audio, "prototype", {
    value: this.HTMLAudioElement.prototype,
    configurable: false,
    enumerable: false,
    writable: false
  });
  Object.defineProperty(window, "Audio", {
    value: Audio,
    configurable: true,
    enumerable: false,
    writable: true
  });

  this.postMessage = postMessage;

  this.atob = function (str) {
    const result = atob(str);
    if (result === null) {
      throw new DOMException("The string to be decoded contains invalid characters.", "InvalidCharacterError");
    }
    return result;
  };

  this.btoa = function (str) {
    const result = btoa(str);
    if (result === null) {
      throw new DOMException("The string to be encoded contains invalid characters.", "InvalidCharacterError");
    }
    return result;
  };

  this.FileReader = createFileReader({
    window: this
  }).interface;
  this.WebSocket = createWebSocket({
    window: this
  }).interface;

  const AbortSignalWrapper = createAbortSignal({
    window: this
  });
  this.AbortSignal = AbortSignalWrapper.interface;
  this.AbortController = createAbortController({
    AbortSignal: AbortSignalWrapper
  }).interface;

  this.XMLHttpRequest = createXMLHttpRequest(this);

  // TODO: necessary for Blob and FileReader due to different-globals weirdness; investigate how to avoid this.
  this.ArrayBuffer = ArrayBuffer;
  this.Int8Array = Int8Array;
  this.Uint8Array = Uint8Array;
  this.Uint8ClampedArray = Uint8ClampedArray;
  this.Int16Array = Int16Array;
  this.Uint16Array = Uint16Array;
  this.Int32Array = Int32Array;
  this.Uint32Array = Uint32Array;
  this.Float32Array = Float32Array;
  this.Float64Array = Float64Array;

  this.stop = function () {
    const manager = idlUtils.implForWrapper(this._document)._requestManager;
    if (manager) {
      manager.close();
    }
  };

  this.close = function () {
    // Recursively close child frame windows, then ourselves.
    const currentWindow = this;
    (function windowCleaner(windowToClean) {
      for (let i = 0; i < windowToClean.length; i++) {
        windowCleaner(windowToClean[i]);
      }

      // We"re already in our own window.close().
      if (windowToClean !== currentWindow) {
        windowToClean.close();
      }
    }(this));

    // Clear out all listeners. Any in-flight or upcoming events should not get delivered.
    idlUtils.implForWrapper(this)._eventListeners = Object.create(null);

    if (this._document) {
      if (this._document.body) {
        this._document.body.innerHTML = "";
      }

      if (this._document.close) {
        // It's especially important to clear out the listeners here because document.close() causes a "load" event to
        // fire.
        idlUtils.implForWrapper(this._document)._eventListeners = Object.create(null);
        this._document.close();
      }
      const doc = idlUtils.implForWrapper(this._document);
      if (doc._requestManager) {
        doc._requestManager.close();
      }
      delete this._document;
    }

    this.__stopAllTimers();
    WebSocketImpl.cleanUpWindow(this);
  };

  this.getComputedStyle = function (elt) {
    elt = Element.convert(elt);

    const declaration = new CSSStyleDeclaration();
    const { forEach, indexOf } = Array.prototype;
    const { style } = elt;

    function setPropertiesFromRule(rule) {
      if (!rule.selectorText) {
        return;
      }

      const cssSelectorSplitRe = /((?:[^,"']|"[^"]*"|'[^']*')+)/;
      const selectors = rule.selectorText.split(cssSelectorSplitRe);
      let matched = false;

      for (const selectorText of selectors) {
        if (selectorText !== "" && selectorText !== "," && !matched && matchesDontThrow(elt, selectorText)) {
          matched = true;
          forEach.call(rule.style, property => {
            declaration.setProperty(
              property,
              rule.style.getPropertyValue(property),
              rule.style.getPropertyPriority(property)
            );
          });
        }
      }
    }

    function readStylesFromStyleSheet(sheet) {
      forEach.call(sheet.cssRules, rule => {
        if (rule.media) {
          if (indexOf.call(rule.media, "screen") !== -1) {
            forEach.call(rule.cssRules, setPropertiesFromRule);
          }
        } else {
          setPropertiesFromRule(rule);
        }
      });
    }

    if (!parsedDefaultStyleSheet) {
      parsedDefaultStyleSheet = cssom.parse(defaultStyleSheet);
    }
    readStylesFromStyleSheet(parsedDefaultStyleSheet);
    forEach.call(elt.ownerDocument.styleSheets, readStylesFromStyleSheet);

    forEach.call(style, property => {
      declaration.setProperty(property, style.getPropertyValue(property), style.getPropertyPriority(property));
    });

    return declaration;
  };

  // The captureEvents() and releaseEvents() methods must do nothing
  this.captureEvents = function () {};

  this.releaseEvents = function () {};

  ///// PUBLIC DATA PROPERTIES (TODO: should be getters)

  function wrapConsoleMethod(method) {
    return (...args) => {
      window._virtualConsole.emit(method, ...args);
    };
  }

  this.console = {
    assert: wrapConsoleMethod("assert"),
    clear: wrapConsoleMethod("clear"),
    count: wrapConsoleMethod("count"),
    countReset: wrapConsoleMethod("countReset"),
    debug: wrapConsoleMethod("debug"),
    dir: wrapConsoleMethod("dir"),
    dirxml: wrapConsoleMethod("dirxml"),
    error: wrapConsoleMethod("error"),
    group: wrapConsoleMethod("group"),
    groupCollapsed: wrapConsoleMethod("groupCollapsed"),
    groupEnd: wrapConsoleMethod("groupEnd"),
    info: wrapConsoleMethod("info"),
    log: wrapConsoleMethod("log"),
    table: wrapConsoleMethod("table"),
    time: wrapConsoleMethod("time"),
    timeEnd: wrapConsoleMethod("timeEnd"),
    trace: wrapConsoleMethod("trace"),
    warn: wrapConsoleMethod("warn")
  };

  function notImplementedMethod(name) {
    return function () {
      notImplemented(name, window);
    };
  }

  define(this, {
    name: "",
    status: "",
    devicePixelRatio: 1,
    innerWidth: 1024,
    innerHeight: 768,
    outerWidth: 1024,
    outerHeight: 768,
    pageXOffset: 0,
    pageYOffset: 0,
    screenX: 0,
    screenLeft: 0,
    screenY: 0,
    screenTop: 0,
    scrollX: 0,
    scrollY: 0,

    alert: notImplementedMethod("window.alert"),
    blur: notImplementedMethod("window.blur"),
    confirm: notImplementedMethod("window.confirm"),
    focus: notImplementedMethod("window.focus"),
    moveBy: notImplementedMethod("window.moveBy"),
    moveTo: notImplementedMethod("window.moveTo"),
    open: notImplementedMethod("window.open"),
    print: notImplementedMethod("window.print"),
    prompt: notImplementedMethod("window.prompt"),
    resizeBy: notImplementedMethod("window.resizeBy"),
    resizeTo: notImplementedMethod("window.resizeTo"),
    scroll: notImplementedMethod("window.scroll"),
    scrollBy: notImplementedMethod("window.scrollBy"),
    scrollTo: notImplementedMethod("window.scrollTo")
  });

  ///// INITIALIZATION

  process.nextTick(() => {
    if (!window.document) {
      return; // window might've been closed already
    }

    if (window.document.readyState === "complete") {
      fireAnEvent("load", window, undefined, {}, window.document);
    } else {
      window.document.addEventListener("load", () => {
        fireAnEvent("load", window, undefined, {}, window.document);

        if (!idlUtils.implForWrapper(window._document)._pageShowingFlag) {
          idlUtils.implForWrapper(window._document)._pageShowingFlag = true;
          fireAnEvent("pageshow", window, PageTransitionEvent, { persisted: false }, window.document);
        }
      });
    }
  });
}
NOTE: per https://heycam.github.io/webidl/#Global, all properties on the Window object must be own-properties. That is why we assign everything inside of the constructor, instead of using a shared prototype. You can verify this in e.g. Firefox or Internet Explorer, which do a good job with Web IDL compliance.