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 WindowTimers, WindowBase64, and WindowEventHandlers.

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.caches Read only

Returns the CacheStorage object associated with the current origin. This object enables service worker functionality such as storing assets for offline use, and generating custom responses to requests.

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.controllers Read 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.orientation Read 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.scrollMaxX Read only

The maximum offset that the window can be scrolled to horizontally, that is the document width minus the viewport width.

Window.scrollMaxY Read 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.

Methods

This interface inherits methods from the EventTarget interface and implements methods from WindowTimers, WindowBase64, WindowEventHandlers, and GlobalFetch.

EventTarget.addEventListener()

Register an event handler to a specific event type on the window.

Window.alert()

Displays an alert dialog.

WindowBase64.atob()

Decodes a string of data which has been encoded using base-64 encoding.

Window.back()

Moves back one in the window history.

Window.blur()

Sets focus away from the window.

WindowBase64.btoa()

Creates a base-64 encoded ASCII string from a string of binary data.

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.

WindowTimers.clearInterval()

Cancels the repeated execution set using WindowTimers.setInterval().

WindowTimers.clearTimeout()

Cancels the repeated execution set using WindowTimers.setTimeout().

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

FIXME: NeedsContents

Window.dispatchEvent()

Used to trigger an event.

Window.dump()

Writes a message to the console.

Window.enableExternalCapture() Obsolete since Gecko 24

FIXME: NeedsContents

GlobalFetch.fetch()

Starts the process of fetching a resource.

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()

FIXME: NeedsContents

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()

FIXME: NeedsContents

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.removeEventListener()

Removes an event listener from the window.

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()

FIXME: NeedsContents

Window.routeEvent() Obsolete since Gecko 24

FIXME: NeedsContents

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

WindowTimers.setInterval()

Schedules the execution of a function each X milliseconds.

Window.setResizable()

Toggles a user's ability to resize a window.

WindowTimers.setTimeout()

Sets a delay for executing a function.

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).

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 WindowTimers, WindowBase64, and WindowEventHandlers.

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.oninstall

Called when the page is installed as a webapp. See install 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

See also the DOM Interfaces.

Window.DOMParser

FIXME: NeedsContents

Window.GeckoActiveXObject

FIXME: NeedsContents

Image

Used for creating an HTMLImageElement.

Option

Used for creating an HTMLOptionElement

Window.QueryInterface

FIXME: NeedsContents

Window.XMLSerializer

FIXME: NeedsContents

Worker

Used for creating a Web worker

Window.XPCNativeWrapper

FIXME: NeedsContents

Window.XPCSafeJSObjectWrapper

FIXME: NeedsContents

Interfaces

See DOM Reference

See also

• Working with windows in chrome code