Window

Instance properties

This interface inherits properties from the EventTarget interface.

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

Window.caches Read only Secure context

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.

Window.clientInformation Read only

An alias for Window.navigator.

Window.closed Read only

This property indicates whether the current window is closed or not.

Window.cookieStore Read only Secure context

Returns a reference to the CookieStore object for the current document context.

Window.crashReport Read only Secure context

Returns a CrashReportContext object that enables arbitrary data to be recorded for the current top-level browsing context, which is then added to a CrashReport and sent to a reporting endpoint when a browser crash occurs.

Window.credentialless Read only

Returns a boolean that indicates whether the current document was loaded inside a credentialless <iframe>. See IFrame credentialless for more details.

Window.crossOriginIsolated Read only

Returns a boolean value that indicates whether the website is in a cross-origin isolation state.

Window.crypto Read only

Returns the Crypto object associated to the global object.

Window.customElements Read only

Returns a reference to the CustomElementRegistry object, which can be used to register new custom elements and get information about previously registered custom elements.

Window.devicePixelRatio Read only

Returns the ratio between physical pixels and device independent pixels in the current display.

Window.document Read only

Returns a reference to the document that the window contains.

Window.documentPictureInPicture Read only Secure context

Returns a reference to the document Picture-in-Picture window for the current document context.

Window.fence Read only

Returns a Fence object instance for the current document context. Available only to documents embedded inside a <fencedframe>.

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.history Read only

Returns a reference to the history object.

Window.indexedDB Read only

Provides a mechanism for applications to asynchronously access capabilities of indexed databases; returns an IDBFactory object.

Window.innerHeight Read only

Gets the height of the content area of the browser window including, if rendered, the horizontal scrollbar.

Window.innerWidth Read only

Gets the width of the content area of the browser window including, if rendered, the vertical scrollbar.

Window.isSecureContext Read only

Returns a boolean indicating whether the current context is secure (true) or not (false).

Window.launchQueue Read only

When a progressive web app (PWA) is launched with a launch_handler client_mode value of focus-existing, navigate-new, or navigate-existing, the launchQueue provides access to the LaunchQueue class, which allows custom launch navigation handling to be implemented for the PWA.

Window.length Read only

Returns the number of frames in the window. See also window.frames.

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.location

Gets/sets the location, or current URL, of the window object.

Window.locationbar Read only

Returns the locationbar object.

Window.menubar Read only

Returns the menubar object.

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.name

Gets/sets the name of the window.

Window.navigation Read only

Returns the current window's associated Navigation object. The entry point for the Navigation API.

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.origin Read only

Returns the global object's origin, serialized as a string.

Window.originAgentCluster Read only

Returns true if this window belongs to an origin-keyed agent cluster.

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.pageYOffset Read only

An alias for window.scrollY.

Window.parent Read only

Returns a reference to the parent of the current window or subframe.

Window.performance Read only

Returns a Performance object, which includes the timing and navigation attributes, each of which is an object providing performance-related data. See also Using Navigation Timing for additional information and examples.

Window.personalbar Read only

Returns the personalbar object.

Window.scheduler Read only

Returns the Scheduler object associated with the current context. This is the entry point for using the Prioritized Task Scheduling API.

Window.screen Read only

Returns a reference to the screen object associated with the window.

Window.screenX and Window.screenLeft Read only

Both properties return the horizontal distance from the left border of the user's browser viewport to the left side of the screen.

Window.screenY and Window.screenTop Read only

Both properties return the vertical distance from the top border of the user's browser viewport to the top side of the screen.

Window.scrollbars Read only

Returns the scrollbars object.

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 reference to the session storage object used to store data that may only be accessed by the origin that created it.

Window.sharedStorage Read only Secure context

Returns the WindowSharedStorage object for the current origin. This is the main entry point for writing data to shared storage using the Shared Storage API.

Window.speechSynthesis Read only

Returns a SpeechSynthesis object, which is the entry point into using Web Speech API speech synthesis functionality.

Window.statusbar Read only

Returns the statusbar object.

Window.toolbar Read only

Returns the toolbar object.

Window.top Read only

Returns a reference to the topmost window in the window hierarchy. This property is read only.

Window.trustedTypes Read only

Returns the TrustedTypePolicyFactory object associated with the global object, providing the entry point for using the Trusted Types API.

Window.viewport Read only

Returns a Viewport object instance, which provides information about the current state of the device's viewport.

Window.visualViewport Read only

Returns a VisualViewport object which represents the visual viewport for a given window.

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.

Named properties

Some elements in the document are also exposed as window properties:

• For each <embed>, <form>, <iframe>, <img>, and <object> element, its name (if non-empty) is exposed. For example, if the document contains <form name="my_form">, then window["my_form"] (and its equivalent window.my_form) returns a reference to that element.
• For each HTML element, its id (if non-empty) is exposed.

If a property corresponds to a single element, that element is directly returned. If the property corresponds to multiple elements, then an HTMLCollection is returned containing all of them. If any of the elements is a navigable <iframe> or <object>, then the contentWindow of first such iframe is returned instead.

Deprecated properties

Window.event Read only

Returns the current event, which is the event currently being handled by the JavaScript code's context, or undefined if no event is currently being handled. The Event object passed directly to event handlers should be used instead whenever possible.

Window.external Read only

Returns an object with functions for adding external search providers to the browser.

Window.orientation Read only

Returns the orientation in degrees (in 90 degree increments) of the viewport relative to the device's natural orientation.

Window.status

Gets/sets the text in the statusbar at the bottom of the browser.

Instance methods

This interface inherits methods from the EventTarget interface.

Window.atob()

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

Window.alert()

Displays an alert dialog.

Window.blur()

Sets focus away from the window.

Window.btoa()

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

Window.cancelAnimationFrame()

Enables you to cancel a callback previously scheduled with Window.requestAnimationFrame.

Window.cancelIdleCallback()

Enables you to cancel a callback previously scheduled with Window.requestIdleCallback.

Window.clearInterval()

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

Window.clearTimeout()

Cancels the delayed execution set using Window.setTimeout().

Window.close()

Closes the current window.

Window.confirm()

Displays a dialog with a message that the user needs to respond to.

Window.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.

Window.dump()

Writes a message to the console.

Window.fetch()

Starts the process of fetching a resource from the network.

Window.fetchLater()

Creates a deferred fetch, which is sent once the page is navigated away from (it is destroyed or enters the bfcache), or after a provided activateAfter timeout whichever comes first.

Window.find()

Searches for a given string in a window.

Window.focus()

Sets focus on the current window.

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.getScreenDetails() Secure context

Returns a Promise that fulfills with a ScreenDetails object instance representing the details of all the screens available to the user's device.

Window.getSelection()

Returns the selection object representing the selected item(s).

Window.matchMedia()

Returns a MediaQueryList object representing the specified media query string.

Window.moveBy()

Moves the current window by a specified amount.

Window.moveTo()

Moves the window to the specified coordinates.

Opens a new 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.queryLocalFonts() Secure context

Returns a Promise that fulfills with an array of FontData objects representing the font faces available locally.

Window.queueMicrotask()

Queues a microtask to be executed at a safe time prior to control returning to the browser's event loop.

Window.reportError()

Reports an error in a script, emulating an unhandled exception.

Window.requestAnimationFrame()

Tells the browser that an animation is in progress, requesting that the browser schedule a repaint of the window for the next animation frame.

Window.requestIdleCallback()

Enables the scheduling of tasks during a browser's idle periods.

Window.requestResize()

Updates the size information shared by an embedded document with its embedding parent, but only if the embedded document has opted in to sharing its size information.

Window.resizeBy()

Resizes the current window by a certain amount.

Window.resizeTo()

Dynamically resizes window.

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.setInterval()

Schedules a function to execute every time a given number of milliseconds elapses.

Window.setTimeout()

Schedules a function to execute in a given amount of time.

Window.showDirectoryPicker() Secure context

Displays a directory picker which allows the user to select a directory.

Window.showOpenFilePicker() Secure context

Shows a file picker that allows a user to select a file or multiple files.

Window.showSaveFilePicker() Secure context

Shows a file picker that allows a user to save a file.

Window.sizeToContent()

Sizes the window according to its content.

Window.stop()

This method stops window loading.

Window.structuredClone()

Creates a deep clone of a given value using the structured clone algorithm.

Deprecated methods

Window.captureEvents()

Registers the window to capture all events of the specified type.

Window.clearImmediate()

Cancels the repeated execution set using setImmediate().

Window.releaseEvents()

Releases the window from trapping events of a specific type.

Window.requestFileSystem()

Lets a website or app gain access to a sandboxed file system for its own use.

Window.setImmediate()

Executes a function after the browser has finished other heavy tasks.

Window.setResizable()

Does nothing (no-op). Kept for backward compatibility with Netscape 4.x.

Window.webkitConvertPointFromNodeToPage()

Transforms a WebKitPoint from the node's coordinate system to the page's coordinate system.

Window.webkitConvertPointFromPageToNode()

Transforms a WebKitPoint from the page's coordinate system to the node's coordinate system.

Events

Listen to these events using addEventListener() or by assigning an event listener to the oneventname property of this interface. In addition to the events listed below, many events can bubble from the Document contained in the window object.

error

Fired when a resource failed to load, or can't be used. For example, if a script has an execution error or an image can't be found or is invalid.

languagechange

Fired at the global scope object when the user's preferred language changes.

resize

Fired when the window has been resized.

storage

Fired when a storage area (localStorage or sessionStorage) has been modified in the context of another document.

Connection events

offline

Fired when the browser has lost access to the network and the value of navigator.onLine has switched to false.

online

Fired when the browser has gained access to the network and the value of navigator.onLine has switched to true.

Device orientation events

devicemotion Secure context

Fired at a regular interval, indicating the amount of physical force of acceleration the device is receiving and the rate of rotation, if available.

deviceorientation Secure context

Fired when fresh data is available from the magnetometer orientation sensor about the current orientation of the device as compared to the Earth coordinate frame.

deviceorientationabsolute Secure context

Fired when fresh data is available from the magnetometer orientation sensor about the current absolute orientation of the device as compared to the Earth coordinate frame.

Focus events

blur

Fired when an element has lost focus.

focus

Fired when an element has gained focus.

Gamepad events

gamepadconnected

Fired when the browser detects that a gamepad has been connected or the first time a button/axis of the gamepad is used.

gamepaddisconnected

Fired when the browser detects that a gamepad has been disconnected.

History events

hashchange

Fired when the fragment identifier of the URL has changed (the part of the URL beginning with and following the # symbol).

pagehide

Sent when the browser hides the current document while in the process of switching to displaying in its place a different document from the session's history. This happens, for example, when the user clicks the Back button or when they click the Forward button to move ahead in session history.

pagereveal

Fired when a document is first rendered, either when loading a fresh document from the network or activating a document (either from back/forward cache (bfcache) or prerender).

pageshow

Sent when the browser makes the document visible due to navigation tasks, including not only when the page is first loaded, but also situations such as the user navigating back to the page after having navigated to another within the same tab.

pageswap

Fired when a document is about to be unloaded due to a navigation.

popstate

Fired when the active history entry changes.

Load & unload events

beforeunload

Fired when the window, the document and its resources are about to be unloaded.

load

Fired when the whole page has loaded, including all dependent resources such as stylesheets images.

unload

Fired when the document or a child resource is being unloaded.

Manifest events

appinstalled

Fired when the browser has successfully installed a page as an application.

beforeinstallprompt

Fired when a user is about to be prompted to install a web application.

Messaging events

message

Fired when the window receives a message, for example from a call to Window.postMessage() from another browsing context.

messageerror

Fired when a Window object receives a message that can't be deserialized.

Print events

afterprint

Fired after the associated document has started printing or the print preview has been closed.

beforeprint

Fired when the associated document is about to be printed or previewed for printing.

Promise rejection events

rejectionhandled

Sent every time a JavaScript Promise is rejected, regardless of whether or not there is a handler in place to catch the rejection.

unhandledrejection

Sent when a JavaScript Promise is rejected but there is no handler in place to catch the rejection.

Scroll events

scrollsnapchange

Fired on the scroll container at the end of a scrolling operation when a new scroll snap target has been selected.

scrollsnapchanging

Fired on the scroll container when the browser determines a new scroll snap target is pending, i.e., it will be selected when the current scroll gesture ends.

Deprecated events

orientationchange

Fired when the orientation of the device has changed.

vrdisplayactivate

Fired when a display is able to be presented to.

vrdisplayconnect

Fired when a compatible VR device has been connected to the computer.

vrdisplaydisconnect

Fired when a compatible VR device has been disconnected from the computer.

vrdisplaydeactivate

Fired when a display can no longer be presented to.

vrdisplaypresentchange

Fired when the presenting state of a VR device changes i.e., goes from presenting to not presenting, or vice versa.

Bubbled events

Not all events that bubble can reach the Window object. Only the following do and can be listened for on the Window object:

• abort
• auxclick
• beforeinput
• beforematch
• beforetoggle
• cancel
• canplay
• canplaythrough
• change
• click
• close
• contextlost
• contextmenu
• contextrestored
• copy
• cuechange
• cut
• dblclick
• drag
• dragend
• dragenter
• dragleave
• dragover
• dragstart
• drop
• durationchange
• emptied
• ended
• formdata
• input
• invalid
• keydown
• keypress
• keyup
• loadeddata
• loadedmetadata
• loadstart
• mousedown
• mouseenter
• mouseleave
• mousemove
• mouseout
• mouseover
• mouseup
• paste
• pause
• play
• playing
• progress
• ratechange
• reset
• scrollend
• securitypolicyviolation
• seeked
• seeking
• select
• slotchange
• stalled
• submit
• suspend
• timeupdate
• toggle
• volumechange
• waiting
• wheel

Interfaces

See DOM Reference.

Listening for events on Window

HTML elements have three ways to listen for events:

• Add an event listener to the element using the EventTarget.addEventListener method.
• Assign an event handler to the element's oneventname property in JavaScript.
• Add an on-prefixed attribute to the element in the HTML.

To listen for events on Window objects, in general, you can only use the first two methods, because Window has no corresponding HTML element. However, there's a specific group of events whose listeners can be added to the <body> (or the deprecated <frameset>) element that's owned by the Window's document, using the second or third methods. These events are:

• afterprint
• beforeprint
• beforeunload
• blur
• error
• focus
• hashchange
• languagechange
• load
• message
• messageerror
• offline
• online
• pagehide
• pagereveal
• pageshow
• pageswap
• popstate
• rejectionhandled
• resize
• scroll
• storage
• unhandledrejection
• unload

This means the following are strictly equivalent:

window.onresize = (e) => console.log(e.currentTarget);
document.body.onresize = (e) => console.log(e.currentTarget);

<body ></body>

In all three cases, you see the Window object logged as currentTarget.

Specifications

Browser compatibility