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/DOM

Window

The window object represents a window containing a DOM document; the document property points to the DOM document loaded in that window. A window for a given document can be obtained using the document.defaultView property.

This section provides a brief reference for all of the methods, properties, and events available through the DOM window object. The window object implements the Window interface, which in turn inherits from the AbstractView interface. Some additional global functions, namespaces, objects, interfaces, and constructors, not typically associated with the window, but available on it, are listed in the JavaScript Reference and DOM Reference.

In a tabbed browser, such as Firefox, each tab contains its own window object (and if you're writing an extension, the browser window itself is a separate window too - see Working with windows in chrome code for more information). That is, the window object is not shared between tabs in the same window. Some methods, namely window.resizeTo and window.resizeBy apply to the whole window and not to the specific tab the window object belongs to. Generally, anything that can't reasonably pertain to a tab pertains to the window instead.

Properties

This interface inherits properties from the EventTarget interface and implements properties from the WindowOrWorkerGlobalScope and WindowEventHandlers mixins.

Note that properties which are objects (e.g.,. for overriding the prototype of built-in elements) are listed in a separate section below.

Window.applicationCache Read only: An OfflineResourceList object providing access to the offline resources for the window.
Window.closed Read only: This property indicates whether the current window is closed or not.
Window.Components: The entry point to many XPCOM features. Some properties, e.g. classes, are only available to sufficiently privileged code. Web code should not use this property.
Window.console Read only: Returns a reference to the console object which provides access to the browser's debugging console.
Window.content and Window._content Read only: Returns a reference to the content element in the current window. The obsolete variant with underscore is no longer available from Web content.
Window.controllersRead only: Returns the XUL controller objects for the current chrome window.
Window.crypto Read only: Returns the browser crypto object.
Window.defaultStatus Obsolete since Gecko 23: Gets/sets the status bar text for the given window.
Window.devicePixelRatio Read only: Returns the ratio between physical pixels and device independent pixels in the current display.
Window.dialogArguments Read only: Gets the arguments passed to the window (if it's a dialog box) at the time window.showModalDialog() was called. This is an nsIArray.
Window.directories: Synonym of window.personalbar
Window.document Read only: Returns a reference to the document that the window contains.
Window.frameElement Read only: Returns the element in which the window is embedded, or null if the window is not embedded.
Window.frames Read only: Returns an array of the subframes in the current window.
Window.fullScreen: This property indicates whether the window is displayed in full screen or not.
Window.globalStorage Obsolete since Gecko 13: Unsupported since Gecko 13 (Firefox 13). Use Window.localStorage instead.
Was: Multiple storage objects that are used for storing data across multiple pages.
Window.history Read only: Returns a reference to the history object.
Window.innerHeight: Gets the height of the content area of the browser window including, if rendered, the horizontal scrollbar.
Window.innerWidth: Gets the width of the content area of the browser window including, if rendered, the vertical scrollbar.
Window.isSecureContext Read only: Indicates whether a context is capable of using features that require secure contexts.
Window.length Read only: Returns the number of frames in the window. See also window.frames.
Window.location Read only: Gets/sets the location, or current URL, of the window object.
Window.locationbar Read only: Returns the locationbar object, whose visibility can be toggled in the window.
Window.localStorage Read only: Returns a reference to the local storage object used to store data that may only be accessed by the origin that created it.
Window.menubar Read only: Returns the menubar object, whose visibility can be toggled in the window.
Window.messageManager: Returns the message manager object for this window.
Window.mozAnimationStartTime Read only: The time in milliseconds since epoch at which the current animation cycle began.
Window.mozInnerScreenX Read only: Returns the horizontal (X) coordinate of the top-left corner of the window's viewport, in screen coordinates. This value is reported in CSS pixels. See mozScreenPixelsPerCSSPixel in nsIDOMWindowUtils for a conversion factor to adapt to screen pixels if needed.
Window.mozInnerScreenY Read only: Returns the vertical (Y) coordinate of the top-left corner of the window's viewport, in screen coordinates. This value is reported in CSS pixels. See mozScreenPixelsPerCSSPixel for a conversion factor to adapt to screen pixels if needed.
Window.mozPaintCount Read only: Returns the number of times the current document has been rendered to the screen in this window. This can be used to compute rendering performance.
Window.name: Gets/sets the name of the window.
Window.navigator Read only: Returns a reference to the navigator object.
Window.opener: Returns a reference to the window that opened this current window.
Window.orientationRead only: Returns the orientation in degrees (in 90 degree increments) of the viewport relative to the device's natural orientation.
Window.outerHeight Read only: Gets the height of the outside of the browser window.
Window.outerWidth Read only: Gets the width of the outside of the browser window.
Window.pageXOffset Read only: An alias for window.scrollX.
Window.pageYOffsetRead only: An alias for window.scrollY
Window.sessionStorage Read only: Returns a reference to the session storage object used to store data that may only be accessed by the origin that created it.
Window.parent Read only: Returns a reference to the parent of the current window or subframe.
Window.performance Read only: Provides a hosting area for performance related attributes.
Window.personalbar Read only: Returns the personalbar object, whose visibility can be toggled in the window.
Window.pkcs11 Obsolete since Gecko 29: Formerly provided access to install and remove PKCS11 modules.
Window.returnValue: The return value to be returned to the function that called window.showModalDialog() to display the window as a modal dialog.
Window.screen Read only: Returns a reference to the screen object associated with the window.
Window.screenX Read only: Returns the horizontal distance of the left border of the user's browser from the left side of the screen.
Window.screenY Read only: Returns the vertical distance of the top border of the user's browser from the top side of the screen.
Window.scrollbars Read only: Returns the scrollbars object, whose visibility can be toggled in the window.
Window.scrollMaxXRead only: The maximum offset that the window can be scrolled to horizontally, that is the document width minus the viewport width.
Window.scrollMaxYRead only: The maximum offset that the window can be scrolled to vertically (i.e., the document height minus the viewport height).
Window.scrollX Read only: Returns the number of pixels that the document has already been scrolled horizontally.
Window.scrollY Read only: Returns the number of pixels that the document has already been scrolled vertically.
Window.self Read only: Returns an object reference to the window object itself.
Window.sessionStorage: Returns a storage object for storing data within a single page session.
Window.sidebar Read only: Returns a reference to the window object of the sidebar.
Window.speechSynthesis Read only: Returns a SpeechSynthesis object, which is the entry point into using Web Speech API speech synthesis functionality.
Window.status: Gets/sets the text in the statusbar at the bottom of the browser.
Window.statusbar Read only: Returns the statusbar object, whose visibility can be toggled in the window.
Window.toolbar Read only: Returns the toolbar object, whose visibility can be toggled in the window.
Window.top Read only: Returns a reference to the topmost window in the window hierarchy. This property is read only.
Window.window Read only: Returns a reference to the current window.
window[0], window[1], etc.: Returns a reference to the window object in the frames. See Window.frames for more details.

Properties implemented from elsewhere

WindowOrWorkerGlobalScope.caches Read only: Returns the CacheStorage object associated with the current context. This object enables functionality such as storing assets for offline use, and generating custom responses to requests.
WindowOrWorkerGlobalScope.indexedDB Read only: Provides a mechanism for applications to asynchronously access capabilities of indexed databases; returns an IDBFactory object.
WindowOrWorkerGlobalScope.isSecureContext Read only: Returns a boolean indicating whether the current context is secure (true) or not (false).
WindowOrWorkerGlobalScope.origin Read only: Returns the global object's origin, serialized as a string. (This does not yet appear to be implemented in any browser.)

Methods

This interface inherits methods from the EventTarget interface and implements methods from WindowOrWorkerGlobalScope and EventTarget.

Window.alert(): Displays an alert dialog.
Window.back(): Moves back one in the window history.
Window.blur(): Sets focus away from the window.
Window.cancelIdleCallback(): Enables you to cancel a callback previously scheduled with Window.requestIdleCallback.
Window.captureEvents(): Registers the window to capture all events of the specified type.
Window.clearImmediate(): Cancels the repeated execution set using setImmediate.
Window.close(): Closes the current window.
Window.confirm(): Displays a dialog with a message that the user needs to respond to.
Window.disableExternalCapture() Obsolete since Gecko 24
Window.dispatchEvent(): Used to trigger an event.
Window.dump(): Writes a message to the console.
Window.enableExternalCapture() Obsolete since Gecko 24
Window.find(): Searches for a given string in a window.
Window.focus(): Sets focus on the current window.
Window.forward(): Moves the window one document forward in the history.
Window.getAttention(): Flashes the application icon.
Window.getAttentionWithCycleCount()
Window.getComputedStyle(): Gets computed style for the specified element. Computed style indicates the computed values of all CSS properties of the element.
Window.getDefaultComputedStyle(): Gets default computed style for the specified element, ignoring author stylesheets.
Window.getSelection(): Returns the selection object representing the selected item(s).
Window.home(): Returns the browser to the home page.
Window.matchMedia(): Returns a MediaQueryList object representing the specified media query string.
Window.maximize()
Window.minimize() (top-level XUL windows only): Minimizes the window.
Window.moveBy(): Moves the current window by a specified amount.
Window.moveTo(): Moves the window to the specified coordinates.
Window.mozRequestAnimationFrame(): Tells the browser that an animation is in progress, requesting that the browser schedule a repaint of the window for the next animation frame. This will cause a MozBeforePaint event to fire before that repaint occurs.
Window.open(): Opens a new window.
Window.openDialog(): Opens a new dialog window.
Window.postMessage(): Provides a secure means for one window to send a string of data to another window, which need not be within the same domain as the first.
Window.print(): Opens the Print Dialog to print the current document.
Window.prompt(): Returns the text entered by the user in a prompt dialog.
Window.releaseEvents(): Releases the window from trapping events of a specific type.
Window.requestIdleCallback(): Enables the scheduling of tasks during a browser's idle periods.
Window.resizeBy(): Resizes the current window by a certain amount.
Window.resizeTo(): Dynamically resizes window.
Window.restore()
Window.routeEvent() Obsolete since Gecko 24
Window.scroll(): Scrolls the window to a particular place in the document.
Window.scrollBy(): Scrolls the document in the window by the given amount.
Window.scrollByLines(): Scrolls the document by the given number of lines.
Window.scrollByPages(): Scrolls the current document by the specified number of pages.
Window.scrollTo(): Scrolls to a particular set of coordinates in the document.
Window.setCursor(): Changes the cursor for the current window
Window.setImmediate(): Executes a function after the browser has finished other heavy tasks
Window.setResizable(): Toggles a user's ability to resize a window.
Window.showModalDialog(): Displays a modal dialog.
Window.sizeToContent(): Sizes the window according to its content.
Window.stop(): This method stops window loading.
Window.updateCommands(): Updates the state of commands of the current chrome window (UI).

Methods implemented from elsewhere

EventTarget.addEventListener(): Register an event handler to a specific event type on the window.
WindowOrWorkerGlobalScope.atob(): Decodes a string of data which has been encoded using base-64 encoding.
WindowOrWorkerGlobalScope.btoa(): Creates a base-64 encoded ASCII string from a string of binary data.
WindowOrWorkerGlobalScope.clearInterval(): Cancels the repeated execution set using WindowOrWorkerGlobalScope.setInterval().
WindowOrWorkerGlobalScope.clearTimeout(): Cancels the delayed execution set using WindowOrWorkerGlobalScope.setTimeout().
WindowOrWorkerGlobalScope.createImageBitmap(): Accepts a variety of different image sources, and returns a Promise which resolves to an ImageBitmap. Optionally the source is cropped to the rectangle of pixels originating at (sx, sy) with width sw, and height sh.
WindowOrWorkerGlobalScope.fetch(): Starts the process of fetching a resource from the network.
EventTarget.removeEventListener: Removes an event listener from the window.
WindowOrWorkerGlobalScope.setInterval(): Schedules a function to execute every time a given number of milliseconds elapses.
WindowOrWorkerGlobalScope.setTimeout(): Schedules a function to execute in a given amount of time.

Event handlers

These are properties of the window object that can be set to establish event handlers for the various things that can happen in the window that might be of interest.

This interface inherits event handlers from the EventTarget interface and implements event handlers from WindowEventHandlers.

Note: Starting in Gecko 9.0, you can now use the syntax if ("onabort" in window) to determine whether or not a given event handler property exists. This is because event handler interfaces have been updated to be proper web IDL interfaces. See DOM event handlers for details.

GlobalEventHandlers.onabort: Called when the loading of a resource has been aborted, such as by a user canceling the load while it is still in progress
WindowEventHandlers.onafterprint: Called when the print dialog box is closed. See afterprint event.
WindowEventHandlers.onbeforeprint: Called when the print dialog box is opened. See beforeprint event.
Window.onbeforeinstallprompt: An event handler property dispatched before a user is prompted to save a web site to a home screen on mobile.
WindowEventHandlers.onbeforeunload: An event handler property for before-unload events on the window.
GlobalEventHandlers.onblur: Called after the window loses focus, such as due to a popup.
GlobalEventHandlers.onchange: An event handler property for change events on the window.
GlobalEventHandlers.onclick: Called after the ANY mouse button is pressed & released
GlobalEventHandlers.ondblclick: Called when a double click is made with ANY mouse button.
GlobalEventHandlers.onclose: Called after the window is closed
GlobalEventHandlers.oncontextmenu: Called when the RIGHT mouse button is pressed
Window.ondevicelight: An event handler property for any ambient light levels changes
Window.ondevicemotion: Called if accelerometer detects a change (For mobile devices)
Window.ondeviceorientation: Called when the orientation is changed (For mobile devices)
Window.ondeviceorientationabsolute Chrome only: An event handler property for any device orientation changes.
Window.ondeviceproximity: An event handler property for device proximity event
GlobalEventHandlers.onerror: Called when a resource fails to load OR when an error occurs at runtime. See error event.
GlobalEventHandlers.onfocus: Called after the window receives or regains focus. See focus events.
WindowEventHandlers.onhashchange: An event handler property for hashchange events on the window; called when the part of the URL after the hash mark ("#") changes.
Window.onappinstalled: Called when the page is installed as a webapp. See appinstalled event.
Window.oninput: Called when the value of an <input> element changes
GlobalEventHandlers.onkeydown: Called when you begin pressing ANY key. See keydown event.
GlobalEventHandlers.onkeypress: Called when a key (except Shift, Fn, and CapsLock) is in pressed position. See keypress event.
GlobalEventHandlers.onkeyup: Called when you finish releasing ANY key. See keyup event.
WindowEventHandlers.onlanguagechange: An event handler property for languagechange events on the window.
GlobalEventHandlers.onload: Called after all resources and the DOM are fully loaded. WILL NOT get called when the page is loaded from cache, such as with back button.
WindowEventHandlers.onmessage: Is an EventHandler representing the code to be called when the message event is raised.
GlobalEventHandlers.onmousedown: Called when ANY mouse button is pressed.
GlobalEventHandlers.onmousemove: Called continously when the mouse is moved inside the window.
GlobalEventHandlers.onmouseout: Called when the pointer leaves the window.
GlobalEventHandlers.onmouseover: Called when the pointer enters the window
GlobalEventHandlers.onmouseup: Called when ANY mouse button is released
Window.onmozbeforepaint: An event handler property for the MozBeforePaint event, which is sent before repainting the window if the event has been requested by a call to the Window.mozRequestAnimationFrame() method.
WindowEventHandlers.onoffline: Called when network connection is lost. See offline event.
WindowEventHandlers.ononline: Called when network connection is established. See online event.
WindowEventHandlers.onpagehide: Called when the user navigates away from the page, before the onunload event. See pagehide event.
WindowEventHandlers.onpageshow: Called after all resources and the DOM are fully loaded. See pageshow event.
Window.onpaint: An event handler property for paint events on the window.
WindowEventHandlers.onpopstate: Called when a back putton is pressed.
Window.onrejectionhandled: An event handler for handled Promise rejection events.
GlobalEventHandlers.onreset: Called when a form is reset
GlobalEventHandlers.onresize: Called continuously as you are resizing the window.
GlobalEventHandlers.onscroll: Called when the scroll bar is moved via ANY means. If the resource fully fits in the window, then this event cannot be invoked
GlobalEventHandlers.onwheel: Called when the mouse wheel is rotated around any axis
GlobalEventHandlers.onselect: Called after text in an input field is selected
GlobalEventHandlers.onselectionchange: Is an EventHandler representing the code to be called when the selectionchange event is raised.
WindowEventHandlers.onstorage: Called when there is a change in session storage or local storage. See storage event
GlobalEventHandlers.onsubmit: Called when a form is submitted
WindowEventHandlers.onunhandledrejection: An event handler for unhandled Promise rejection events.
WindowEventHandlers.onunload: Called when the user navigates away from the page.
Window.onuserproximity: An event handler property for user proximity events.
Window.onvrdisplayconnected: Represents an event handler that will run when a compatible VR device has been connected to the computer (when the vrdisplayconnected event fires).
Window.onvrdisplaydisconnected: Represents an event handler that will run when a compatible VR device has been disconnected from the computer (when the vrdisplaydisconnected event fires).
Window.onvrdisplaypresentchange: represents an event handler that will run when the presenting state of a VR device changes — i.e. goes from presenting to not presenting, or vice versa (when the onvrdisplaypresentchange event fires).

Constructors

Interfaces

See DOM Reference