Features missing only in Safari

The following features are implemented in all other browser engines, but not in Safari.

• attr()

  Limited availability

  The attr() CSS function, in the context of any property, returns the value of an attribute of an HTML element, with the option to return it as a specific type or unit. You can set a default value for missing or invalid attributes.

  Learn more

  • Chrome 133 Released on 2025-02-04
  • Chrome Android 133 Released on 2025-02-04
  • Edge 133 Released on 2025-02-06
  • Firefox 155 Released on 2026-09-01
  • Firefox for Android 155 Released on 2026-09-01
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since September 2026 by Safari (1 months)

• autocapitalize

  Limited availability

  The autocapitalize global HTML attribute sets the virtual keyboard capitalization behavior for user input on an element, such as the first letter of sentences or all words.

  Learn more

  • Chrome 66 Released on 2018-04-17
  • Chrome Android 66 Released on 2018-04-17
  • Edge 79 Released on 2020-01-15
  • Firefox 111 Released on 2023-03-14
  • Firefox for Android 111 Released on 2023-03-14
  • Safari Not supported
  • Safari on iOS 10.3 Released on 2017-03-27

  Baseline availability blocked since March 2023 by Safari (43 months)

• background-attachment

  Limited availability

  The background-attachment CSS property sets whether an element's background image or gradient moves as the element scrolls.

  Learn more

  • Chrome 1 Released on 2008-12-11
  • Chrome Android 18 Released on 2012-06-27
  • Edge 12 Released on 2015-07-29
  • Firefox 25 Released on 2013-10-29
  • Firefox for Android 25 Released on 2013-10-29
  • Safari 15.4 Released on 2022-03-14
  • Safari on iOS Not supported

  Baseline availability blocked since March 2022 by Safari (55 months)

• baseline-source

  Limited availability

  The baseline-source CSS property controls how inline-level boxes with multiple lines of text are aligned with the surrounding text. By default, which typographic baseline is used depends on the display property value.

  Learn more

  • Chrome 111 Released on 2023-03-07
  • Chrome Android 111 Released on 2023-03-07
  • Edge 111 Released on 2023-03-13
  • Firefox 115 Released on 2023-07-04
  • Firefox for Android 115 Released on 2023-07-04
  • Safari Not supported Position
  • Safari on iOS Not supported Position

  Baseline availability blocked since July 2023 by Safari (39 months)

• beforeunload

  Limited availability

  The beforeunload event is fired when the current window is about to be unloaded. Typically this is used to display a dialog to confirm if users really want to leave the page when there is unsaved data that would be lost.

  Learn more

  • Chrome 1 Released on 2008-12-11
  • Chrome Android 18 Released on 2012-06-27
  • Edge 12 Released on 2015-07-29
  • Firefox 1 Released on 2004-11-09
  • Firefox for Android 4 Released on 2011-03-29
  • Safari 3 Released on 2007-10-26
  • Safari on iOS Not supported

  Baseline availability blocked since July 2015 by Safari (135 months)

• box-decoration-break

  Limited availability

  The box-decoration-break CSS property sets whether box decorations, such as borders or backgrounds, of an element divided across a page, column, or region wraps each fragment or splits across the break.

  Learn more

  • Chrome 130 Released on 2024-10-15
  • Chrome Android 130 Released on 2024-10-15
  • Edge 130 Released on 2024-10-17
  • Firefox 32 Released on 2014-09-02
  • Firefox for Android 32 Released on 2014-09-02
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since October 2024 by Safari (24 months)

• 2D canvas opacity

  Limited availability

  The optional alpha parameter of a 2D canvas's getContext() method sets whether the canvas has an alpha transparency channel. If set to false, then this permits the browser to optimize compositing for an opaque canvas.

  Learn more

  • Chrome 32 Released on 2014-01-14
  • Chrome Android 32 Released on 2014-01-15
  • Edge 79 Released on 2020-01-15
  • Firefox 30 Released on 2014-06-10
  • Firefox for Android 30 Released on 2014-06-10
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since January 2020 by Safari (81 months)

• contextlost and contextrestored

  Limited availability

  The contextlost event for <canvas> fires when the canvas backing storage is lost, while the contextrestored event fires when it is recreated.

  Learn more

  • Chrome 99 Released on 2022-03-01
  • Chrome Android 99 Released on 2022-03-01
  • Edge 99 Released on 2022-03-03
  • Firefox 125 Released on 2024-04-16
  • Firefox for Android 125 Released on 2024-04-16
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2024 by Safari (30 months)

• captureStream() for <audio> and <video>

  Limited availability

  The captureStream() method for <audio> and <video> elements returns a MediaStream for the media element's content. You can use this to record media or send it elsewhere, such as a canvas or WebRTC connection.

  Learn more

  • Chrome 62 Released on 2017-10-17
  • Chrome Android 62 Released on 2017-10-24
  • Edge 79 Released on 2020-01-15
  • Firefox 149 Released on 2026-03-24
  • Firefox for Android 149 Released on 2026-03-24
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since March 2026 by Safari (7 months)

• CloseWatcher

  Limited availability

  The CloseWatcher API listens and responds to close requests on in-page components, such as modals, popovers, and sidebars.

  Learn more

  • Chrome 126 Released on 2024-06-11
  • Chrome Android 126 Released on 2024-06-11
  • Edge 126 Released on 2024-06-13
  • Firefox 149 Released on 2026-03-24
  • Firefox for Android 149 Released on 2026-03-24
  • Safari Not supported Position: neutral
  • Safari on iOS Not supported Position: neutral

  Baseline availability blocked since March 2026 by Safari (7 months)

• COLRv1

  Limited availability

  COLRv1 is a font format that supports multi-color glyphs. COLRv1 extends COLRv0 to support gradients, transforms, and blending modes.

  Learn more

  • Chrome 98 Released on 2022-02-01
  • Chrome Android 98 Released on 2022-02-01
  • Edge 98 Released on 2022-02-03
  • Firefox 107 Released on 2022-11-15
  • Firefox for Android 107 Released on 2022-11-15
  • Safari Not supported Position
  • Safari on iOS Not supported Position

  Baseline availability blocked since November 2022 by Safari (47 months)

• context-fill and context-stroke

  Limited availability

  The context-fill and context-stroke CSS values are used with fill and stroke in SVG <marker> or <use> elements to match a color from where they appear.

  Learn more

  • Chrome 124 Released on 2024-04-16
  • Chrome Android 124 Released on 2024-04-16
  • Edge 124 Released on 2024-04-18
  • Firefox 111 Released on 2023-03-14
  • Firefox for Android 111 Released on 2023-03-14
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2024 by Safari (30 months)

• Cookie store

  Limited availability

  The CookieStore API is an asynchronous and promise-based API for managing cookies. It does not rely on document and so is available to service workers as well.

  Learn more

  • Chrome 87 Released on 2020-11-17
  • Chrome Android 87 Released on 2020-11-17
  • Edge 87 Released on 2020-11-19
  • Firefox 140 Released on 2025-06-24
  • Firefox for Android 140 Released on 2025-06-24
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since June 2025 by Safari (16 months)

• CSS import attributes

  Limited availability

  Module import … with { type: "css" } statements load CSS modules as constructable stylesheets. Also known as CSS module scripts.

  Learn more

  • Chrome 123 Released on 2024-03-19
  • Chrome Android 123 Released on 2024-03-19
  • Edge 123 Released on 2024-03-22
  • Firefox 147 Released on 2026-01-13
  • Firefox for Android 147 Released on 2026-01-13
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since January 2026 by Safari (9 months)

• Cursor styles

  Limited availability

  The cursor CSS property styles the pointer, allowing you to provide hints to the user on how to interact with the hovered element.

  Learn more

  • Chrome 68 Released on 2018-07-24
  • Chrome Android 68 Released on 2018-07-24
  • Edge 79 Released on 2020-01-15
  • Firefox 27 Released on 2014-02-04
  • Firefox for Android 95 Released on 2021-12-07
  • Safari 11 Released on 2017-09-19
  • Safari on iOS Not supported

  Baseline availability blocked since December 2021 by Safari (58 months)

• Customized built-in elements

  Limited availability

  Customized built-in elements are HTML elements that extend built-in elements using the is attribute, to add new behaviors that you define.

  Learn more

  • Chrome 67 Released on 2018-05-29
  • Chrome Android 67 Released on 2018-05-31
  • Edge 79 Released on 2020-01-15
  • Firefox 63 Released on 2018-10-23
  • Firefox for Android 63 Released on 2018-10-23
  • Safari Not supported Position: oppose
  • Safari on iOS Not supported Position: oppose

  Baseline availability blocked since January 2020 by Safari (81 months)

• devicePixelRatio

  Limited availability

  The window.devicePixelRatio property is the ratio of the size of one CSS pixel to the vertical size of one physical pixel on the current display device.

  Learn more

  • Chrome 1 Released on 2008-12-11
  • Chrome Android 18 Released on 2012-06-27
  • Edge 12 Released on 2015-07-29
  • Firefox 18 Released on 2013-01-08
  • Firefox for Android 18 Released on 2013-01-08
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2015 by Safari (135 months)

• <dialog closedby>

  Limited availability

  The closedby HTML attribute for <dialog> sets which user actions close a dialog. For example, closedby="any" allows the dialog to be closed by clicking outside of it.

  Learn more

  • Chrome 134 Released on 2025-03-04
  • Chrome Android 134 Released on 2025-03-04
  • Edge 134 Released on 2025-03-06
  • Firefox 141 Released on 2025-07-22
  • Firefox for Android 141 Released on 2025-07-22
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since July 2025 by Safari (15 months)

• Explicit resource management

  Limited availability

  The using and await using declarations and the dispose and asyncDispose symbols manage the lifecycle of resources such as file handles and streams. The DisposableStack and AsyncDisposableStack objects can group, dispose, and coordinate dependencies between multiple disposable resources.

  Learn more

  • Chrome 134 Released on 2025-03-04
  • Chrome Android 134 Released on 2025-03-04
  • Edge 134 Released on 2025-03-06
  • Firefox 141 Released on 2025-07-22
  • Firefox for Android 141 Released on 2025-07-22
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2025 by Safari (15 months)

• EXT_float_blend WebGL extension

  Limited availability

  The EXT_float_blend extension for WebGL 1.0 and 2.0 contexts adds 32-bit floating-point components to blending and draw buffers.

  Learn more

  • Chrome 75 Released on 2019-06-04
  • Chrome Android 75 Released on 2019-06-04
  • Edge 79 Released on 2020-01-15
  • Firefox 67 Released on 2019-05-21
  • Firefox for Android 67 Released on 2019-05-21
  • Safari 14.1 Released on 2021-04-26
  • Safari on iOS Not supported

  Baseline availability blocked since April 2021 by Safari (66 months)

• window.external

  The window.external.AddSearchProvider() and window.external.IsSearchProviderInstalled() do nothing. Historically, they added external search providers to the browser.

  Learn more

  • Chrome 9 Released on 2011-02-03
  • Chrome Android 18 Released on 2012-06-27
  • Edge 12 Released on 2015-07-29
  • Firefox 2 Released on 2006-10-24
  • Firefox for Android 4 Released on 2011-03-29
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2015 by Safari (135 months)

• Fetch metadata request headers

  Limited availability

  The Sec-Fetch-Dest, Sec-Fetch-Mode, Sec-Fetch-Site, and Sec-Fetch-User HTTP headers provide extra information about the way a request was made, to help servers reject certain kinds of malicious requests.

  Learn more

  • Chrome 80 Released on 2020-02-04
  • Chrome Android 80 Released on 2020-02-04
  • Edge 80 Released on 2020-02-07
  • Firefox 90 Released on 2021-07-13
  • Firefox for Android 90 Released on 2021-07-13
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2021 by Safari (63 months)

• font-language-override

  Limited availability

  The font-language-override CSS property sets which language-specific glyphs are displayed.

  Learn more

  • Chrome 143 Released on 2025-12-02
  • Chrome Android 143 Released on 2025-12-02
  • Edge 143 Released on 2025-12-05
  • Firefox 34 Released on 2014-12-01
  • Firefox for Android 34 Released on 2014-12-01
  • Safari Not supported Position
  • Safari on iOS Not supported Position

  Baseline availability blocked since December 2025 by Safari (10 months)

• Font metric overrides

  Limited availability

  The ascent-override, descent-override, and line-gap-override descriptors adjust the display of a font declared in an @font-face statement. This can help make fallback fonts look the same size.

  Learn more

  • Chrome 87 Released on 2020-11-17
  • Chrome Android 87 Released on 2020-11-17
  • Edge 87 Released on 2020-11-19
  • Firefox 89 Released on 2021-06-01
  • Firefox for Android 89 Released on 2021-06-01
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since June 2021 by Safari (64 months)

• font-variant-emoji

  Limited availability

  The font-variant-emoji CSS property sets the default presentation for emoji characters.

  Learn more

  • Chrome 131 Released on 2024-11-12
  • Chrome Android 131 Released on 2024-11-12
  • Edge 131 Released on 2024-11-14
  • Firefox 141 Released on 2025-07-22
  • Firefox for Android 141 Released on 2025-07-22
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2025 by Safari (15 months)

• Fullscreen API

  Limited availability

  The fullscreen API makes a specific element fill the whole screen and hides most browser UI.

  Learn more

  • Chrome 71 Released on 2018-12-04
  • Chrome Android 71 Released on 2018-12-04
  • Edge 79 Released on 2020-01-15
  • Firefox 64 Released on 2018-12-11
  • Firefox for Android 64 Released on 2018-12-11
  • Safari 16.4 Released on 2023-03-27
  • Safari on iOS Not supported

  Baseline availability blocked since March 2023 by Safari (43 months)

• Gamepad touch buttons

  Limited availability

  The touched property of a GamepadButton object indicates whether a button capable of detecting touch is currently touched.

  Learn more

  • Chrome 73 Released on 2019-03-12
  • Chrome Android 73 Released on 2019-03-12
  • Edge 15 Released on 2017-04-05
  • Firefox 55 Released on 2017-08-08
  • Firefox for Android 55 Released on 2017-08-08
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since March 2019 by Safari (91 months)

• IndexedDB getAllRecords()

  Limited availability

  The getAllRecords() method of IDBObjectStore and IDBIndex return records and their primary keys from an IndexedDB store or index. The records can be read in batches and in reverse order. The getAllRecords() methods speed up read operations on large datasets.

  Learn more

  • Chrome 141 Released on 2025-09-30
  • Chrome Android 141 Released on 2025-09-30
  • Edge 141 Released on 2025-10-03
  • Firefox 153 Released on 2026-07-21
  • Firefox for Android 153 Released on 2026-07-21
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since July 2026 by Safari (3 months)

• hidden="until-found"

  Limited availability

  The hidden="until-found" attribute hides an element until it is found using the browser's find-in-page search or it is directly navigated to by following a URL fragment.

  Learn more

  • Chrome 102 Released on 2022-05-24
  • Chrome Android 102 Released on 2022-05-24
  • Edge 102 Released on 2022-05-31
  • Firefox 148 Released on 2026-02-24
  • Firefox for Android 148 Released on 2026-02-24
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since February 2026 by Safari (8 months)

• Custom highlights from point

  Limited availability

  The CSS.highlights.highlightsFromPoint() method returns an array of Highlight objects at a specified point.

  Learn more

  • Chrome 140 Released on 2025-09-02
  • Chrome Android 140 Released on 2025-09-02
  • Edge 140 Released on 2025-09-05
  • Firefox 150 Released on 2026-04-21
  • Firefox for Android 150 Released on 2026-04-21
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2026 by Safari (6 months)

• Hyphenate limit chars

  Limited availability

  The hyphenate-limit-chars CSS property sets the number of characters in a word before it is hyphenated and the minimum number of characters on either side of the hyphen.

  Learn more

  • Chrome 109 Released on 2023-01-10
  • Chrome Android 109 Released on 2023-01-10
  • Edge 109 Released on 2023-01-12
  • Firefox 137 Released on 2025-04-01
  • Firefox for Android 137 Released on 2025-04-01
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2025 by Safari (18 months)

• Error.isError()

  Limited availability

  The Error.isError() static method checks whether a value is an Error object.

  Learn more

  • Chrome 134 Released on 2025-03-04
  • Chrome Android 134 Released on 2025-03-04
  • Edge 134 Released on 2025-03-06
  • Firefox 138 Released on 2025-04-29
  • Firefox for Android 138 Released on 2025-04-29
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2025 by Safari (18 months)

• Iterator includes()

  Limited availability

  The includes() method of an Iterator object returns true when an item yielded by the iterator is the same as a given value. It's similar to the includes() method of arrays.

  Learn more

  • Chrome 154 Released on 2026-09-22
  • Chrome Android 154 Released on 2026-09-22
  • Edge 154 Released on 2026-09-24
  • Firefox 154 Released on 2026-08-18
  • Firefox for Android 154 Released on 2026-08-18
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since September 2026 by Safari (1 months)

• Iterator join()

  Limited availability

  The join() method of an Iterator object returns a string concatenation of all the iterator's items, separated by commas or a given separator string. It's similar to the join() method of arrays.

  Learn more

  • Chrome 153 Released on 2026-09-08
  • Chrome Android 153 Released on 2026-09-08
  • Edge 153 Released on 2026-09-11
  • Firefox 154 Released on 2026-08-18
  • Firefox for Android 154 Released on 2026-08-18
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since September 2026 by Safari (1 months)

• Iterator.zip() and Iterator.zipKeyed()

  Limited availability

  The Iterator.zip() and Iterator.zipKeyed() static methods return new iterators that aggregate items from multiple iterables. You can use them to iterate jointly, to get all of the items at the same position in each iterable.

  Learn more

  • Chrome 153 Released on 2026-09-08
  • Chrome Android 153 Released on 2026-09-08
  • Edge 153 Released on 2026-09-11
  • Firefox 148 Released on 2026-02-24
  • Firefox for Android 148 Released on 2026-02-24
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since September 2026 by Safari (1 months)

• <link rel="prefetch">

  Limited availability

  The rel="prefetch" attribute for the <link> HTML element is a hint to the browser that the user is likely to navigate to a resource, so the browser should preemptively fetch and cache the resource.

  Learn more

  • Chrome 8 Released on 2010-12-02
  • Chrome Android 18 Released on 2012-06-27
  • Edge 12 Released on 2015-07-29
  • Firefox 2 Released on 2006-10-24
  • Firefox for Android 4 Released on 2011-03-29
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2015 by Safari (135 months)

• ::marker

  Limited availability

  The ::marker CSS pseudo-element selects list item markers for styling numbers or bullets.

  Learn more

  • Chrome 86 Released on 2020-10-20
  • Chrome Android 86 Released on 2020-10-20
  • Edge 86 Released on 2020-10-09
  • Firefox 80 Released on 2020-08-25
  • Firefox for Android 80 Released on 2020-08-31
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since October 2020 by Safari (72 months)

• Media source

  Limited availability

  The MediaSource API is a custom data source for media elements commonly used for adaptive streaming. Also known as Media Source Extensions (MSE).

  Learn more

  • Chrome 31 Released on 2013-11-12
  • Chrome Android 31 Released on 2013-11-14
  • Edge 12 Released on 2015-07-29
  • Firefox 42 Released on 2015-11-03
  • Firefox for Android 41 Released on 2015-09-22
  • Safari 8 Released on 2014-10-16
  • Safari on iOS Not supported

  Baseline availability blocked since November 2015 by Safari (131 months)

• moveBefore()

  Limited availability

  The moveBefore() DOM method relocates a node while preserving its state. For example, you can move the active element without losing focus, move an animated element without resetting the animation, or move an iframe without reloading its content.

  Learn more

  • Chrome 133 Released on 2025-02-04
  • Chrome Android 133 Released on 2025-02-04
  • Edge 133 Released on 2025-02-06
  • Firefox 144 Released on 2025-10-14
  • Firefox for Android 144 Released on 2025-10-14
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since October 2025 by Safari (12 months)

• Navigation precommit handlers

  Limited availability

  The precommitHandler callback option to NavigateEvent's intercept() method returns a promise that defers navigation until the promise resolves. You can use this to change the navigation's URL, state, and history before navigation occurs.

  Learn more

  • Chrome 146 Released on 2026-03-10
  • Chrome Android 146 Released on 2026-03-10
  • Edge 146 Released on 2026-03-13
  • Firefox 148 Released on 2026-02-24
  • Firefox for Android 148 Released on 2026-02-24
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since March 2026 by Safari (7 months)

• overscroll-behavior

  Limited availability

  The overscroll-behavior CSS property disables default scrolling behaviors when the edges of a scrolling area are reached.

  Learn more

  • Chrome 144 Released on 2026-01-13
  • Chrome Android 144 Released on 2026-01-13
  • Edge 144 Released on 2026-01-21
  • Firefox 150 Released on 2026-04-21
  • Firefox for Android 150 Released on 2026-04-21
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2026 by Safari (6 months)

• page-orientation

  Limited availability

  The page-orientation CSS property sets the rotation of a page after pagination. This allows pages with the same size declaration to display with different orientations.

  Learn more

  • Chrome 85 Released on 2020-08-25
  • Chrome Android 85 Released on 2020-08-25
  • Edge 85 Released on 2020-08-27
  • Firefox 122 Released on 2024-01-23
  • Firefox for Android 122 Released on 2024-01-23
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since January 2024 by Safari (33 months)

• path()

  Limited availability

  The path() CSS shape function creates a shape for clip-path, shape-outside, and the SVG attribute d.

  Learn more

  • Chrome 88 Released on 2021-01-19
  • Chrome Android 88 Released on 2021-01-19
  • Edge 88 Released on 2021-01-21
  • Firefox 97 Released on 2022-02-08
  • Firefox for Android 97 Released on 2022-02-08
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since February 2022 by Safari (56 months)

• Pointer lock

  Limited availability

  Provides access to raw mouse movement by locking the target of mouse events to a single element and hiding the mouse cursor.

  Learn more

  • Chrome 37 Released on 2014-08-26
  • Chrome Android 144 Released on 2026-01-13
  • Edge 13 Released on 2015-11-12
  • Firefox 50 Released on 2016-11-15
  • Firefox for Android 50 Released on 2016-11-15
  • Safari 10.1 Released on 2017-03-27
  • Safari on iOS Not supported

  Baseline availability blocked since January 2026 by Safari (9 months)

• popover="hint"

  Limited availability

  The popover="hint" global HTML attribute creates a popover that is subordinate to popovers with a popover="auto" attribute. You can use this to create tooltips that don't dismiss auto popovers.

  Learn more

  • Chrome 151 Released on 2026-07-28
  • Chrome Android 151 Released on 2026-07-28
  • Edge 151 Released on 2026-07-31
  • Firefox 153 Released on 2026-07-21
  • Firefox for Android 153 Released on 2026-07-21
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2026 by Safari (3 months)

• Crash reporting

  Limited availability

  Crash reporting sends a report to a URL nominated by the Reporting-Endpoints header when a user is unable to continue using the page because the browser or tab crashed.

  Learn more

  • Chrome 96 Released on 2021-11-15
  • Chrome Android 96 Released on 2021-11-15
  • Edge 96 Released on 2021-11-19
  • Firefox 149 Released on 2026-03-24
  • Firefox for Android 149 Released on 2026-03-24
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since March 2026 by Safari (7 months)

• requestIdleCallback()

  Limited availability

  The requestIdleCallback() API queues a function that runs in idle browser time, either at the end of a frame or when the user is inactive. Also known as the background tasks API.

  Learn more

  • Chrome 47 Released on 2015-12-01
  • Chrome Android 47 Released on 2015-12-02
  • Edge 79 Released on 2020-01-15
  • Firefox 55 Released on 2017-08-08
  • Firefox for Android 55 Released on 2017-08-08
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since January 2020 by Safari (81 months)

• Sanitizer API

  Limited availability

  The Sanitizer API customizes the sanitization of HTML parsed and inserted into the DOM in a way that can prevent cross-site scripting attacks. You can use it with DOM APIs that accept a sanitizer option, such as parseHTML() or setHTML().

  Learn more

  • Chrome 146 Released on 2026-03-10
  • Chrome Android 146 Released on 2026-03-10
  • Edge 146 Released on 2026-03-13
  • Firefox 148 Released on 2026-02-24
  • Firefox for Android 148 Released on 2026-02-24
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since March 2026 by Safari (7 months)

• Scheduler API

  Limited availability

  The scheduler API provides a way to prioritize all tasks belonging to an application.

  Learn more

  • Chrome 129 Released on 2024-09-17
  • Chrome Android 129 Released on 2024-09-17
  • Edge 129 Released on 2024-09-19
  • Firefox 142 Released on 2025-08-19
  • Firefox for Android 142 Released on 2025-08-19
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since August 2025 by Safari (14 months)

• ::selection

  Limited availability

  The ::selection CSS pseudo-element selects text a user has highlighted.

  Learn more

  • Chrome 1 Released on 2008-12-11
  • Chrome Android 18 Released on 2012-06-27
  • Edge 12 Released on 2015-07-29
  • Firefox 62 Released on 2018-09-05
  • Firefox for Android 62 Released on 2018-09-05
  • Safari 1.1 Released on 2003-10-24
  • Safari on iOS Not supported

  Baseline availability blocked since September 2018 by Safari (97 months)

• Serializable errors

  Limited availability

  The DOMException, Error, EvalError, RangeError, ReferenceError, SyntaxError, TypeError, and URIError objects are serializable. You can call structuredClone() on an error object or pass it to a worker using postMessage().

  Learn more

  • Chrome 77 Released on 2019-09-10
  • Chrome Android 77 Released on 2019-09-10
  • Edge 79 Released on 2020-01-15
  • Firefox 103 Released on 2022-07-26
  • Firefox for Android 103 Released on 2022-07-26
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2022 by Safari (51 months)

• showPicker() for <input>

  Limited availability

  The showPicker() method for <input> elements shows the user interface for picking a value. For example, for <input type="date"> it shows the interface for picking a date.

  Learn more

  • Chrome 99 Released on 2022-03-01
  • Chrome Android 99 Released on 2022-03-01
  • Edge 99 Released on 2022-03-03
  • Firefox 101 Released on 2022-05-31
  • Firefox for Android 101 Released on 2022-05-31
  • Safari 17.4 Released on 2024-03-05
  • Safari on iOS Not supported

  Baseline availability blocked since March 2024 by Safari (31 months)

• showPicker() for <select>

  Limited availability

  The showPicker() method for <select> elements shows the dropdown menu or other user interface for picking one of the options.

  Learn more

  • Chrome 121 Released on 2024-01-23
  • Chrome Android 121 Released on 2024-01-23
  • Edge 121 Released on 2024-01-25
  • Firefox 122 Released on 2024-01-23
  • Firefox for Android 122 Released on 2024-01-23
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since January 2024 by Safari (33 months)

• <img sizes="auto" loading="lazy">

  Limited availability

  The sizes="auto" attribute for the <img> HTML element sets the layout size for the image based on the computed layout size when choosing a source from the srcset. This attribute only applies to images with the loading="lazy" attribute.

  Learn more

  • Chrome 126 Released on 2024-06-11
  • Chrome Android 126 Released on 2024-06-11
  • Edge 126 Released on 2024-06-13
  • Firefox 150 Released on 2026-04-21
  • Firefox for Android 150 Released on 2026-04-21
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2026 by Safari (6 months)

• at-rule()

  Limited availability

  The at-rule() function, when used with @supports, checks if a CSS at-rule is supported. For example @supports at-rule(@starting-style) checks if the @starting-style at-rule is supported.

  Learn more

  • Chrome 148 Released on 2026-05-05
  • Chrome Android 148 Released on 2026-05-05
  • Edge 148 Released on 2026-05-07
  • Firefox 157 Released on 2026-09-29
  • Firefox for Android 157 Released on 2026-09-29
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since September 2026 by Safari (1 months)

• symbols()

  Limited availability

  The symbols() CSS function defines counter styles as a value of properties such as list-style. It's an inline alternative to the @counter-style CSS at-rule.

  Learn more

  • Chrome 155 Released on 2026-10-06
  • Chrome Android 155 Released on 2026-10-06
  • Edge 155 Released on 2026-10-08
  • Firefox 35 Released on 2015-01-13
  • Firefox for Android 35 Released on 2015-01-13
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since October 2026 by Safari (0 months)

• Temporal

  Limited availability

  The Temporal API allows you to work with dates, times, time zones, and durations. It is more powerful than the Date API.

  Learn more

  • Chrome 144 Released on 2026-01-13
  • Chrome Android 144 Released on 2026-01-13
  • Edge 144 Released on 2026-01-21
  • Firefox 139 Released on 2025-05-27
  • Firefox for Android 139 Released on 2025-05-27
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since January 2026 by Safari (9 months)

• text-justify

  Limited availability

  The text-justify CSS property sets the justification method of text when text-align: justify is set.

  Learn more

  • Chrome 145 Released on 2026-02-10
  • Chrome Android 145 Released on 2026-02-10
  • Edge 145 Released on 2026-02-14
  • Firefox 55 Released on 2017-08-08
  • Firefox for Android 55 Released on 2017-08-08
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since February 2026 by Safari (8 months)

• Text import attributes

  Limited availability

  Module import … with { type: "text" } statements load text data as a string value.

  Learn more

  • Chrome 155 Released on 2026-10-06
  • Chrome Android 155 Released on 2026-10-06
  • Edge 155 Released on 2026-10-08
  • Firefox 153 Released on 2026-07-21
  • Firefox for Android 153 Released on 2026-07-21
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since October 2026 by Safari (0 months)

• Touch events

  Limited availability

  Touch events touchstart, touchmove, touchend, and touchcancel fire when users interact with a touch-sensitive surface, such as a screen or drawing tablet. These events are similar to mouse events.

  Learn more

  • Chrome 22 Released on 2012-09-25
  • Chrome Android 25 Released on 2013-02-27
  • Edge 12 Released on 2015-07-29
  • Firefox 52 Released on 2017-03-07
  • Firefox for Android 6 Released on 2011-08-16
  • Safari Not supported
  • Safari on iOS ≤3 Released before 2009-06-17

  Baseline availability blocked since March 2017 by Safari (115 months)

• Transferable streams

  Limited availability

  Streams are transferable objects, which can be moved between contexts such as windows and workers.

  Learn more

  • Chrome 87 Released on 2020-11-17
  • Chrome Android 87 Released on 2020-11-17
  • Edge 87 Released on 2020-11-19
  • Firefox 103 Released on 2022-07-26
  • Firefox for Android 103 Released on 2022-07-26
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2022 by Safari (51 months)

• user-select

  Limited availability

  The user-select CSS property controls which elements can be selected by the user.

  Learn more

  • Chrome 54 Released on 2016-10-12
  • Chrome Android 54 Released on 2016-10-19
  • Edge 79 Released on 2020-01-15
  • Firefox 69 Released on 2019-09-03
  • Firefox for Android 79 Released on 2020-07-28
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2020 by Safari (75 months)

• Memory64 (WebAssembly)

  Limited availability

  Instructions accept 64-bit memory indexes.

  Learn more

  • Chrome 133 Released on 2025-02-04
  • Chrome Android 133 Released on 2025-02-04
  • Edge 133 Released on 2025-02-06
  • Firefox 134 Released on 2025-01-07
  • Firefox for Android 134 Released on 2025-01-07
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since February 2025 by Safari (20 months)

• Multi-memory (WebAssembly)

  Limited availability

  A single module in WebAssembly can have multiple memories.

  Learn more

  • Chrome 120 Released on 2023-12-05
  • Chrome Android 120 Released on 2023-12-05
  • Edge 120 Released on 2023-12-07
  • Firefox 125 Released on 2024-04-16
  • Firefox for Android 125 Released on 2024-04-16
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since April 2024 by Safari (30 months)

• Relaxed-width SIMD (WebAssembly)

  Limited availability

  Relaxed SIMD (Single Instruction Multiple Data) introduces local non-determinism, where the results of the instructions may vary based on hardware support.

  Learn more

  • Chrome 114 Released on 2023-05-30
  • Chrome Android 114 Released on 2023-05-30
  • Edge 114 Released on 2023-06-02
  • Firefox 146 Released on 2025-12-09
  • Firefox for Android 146 Released on 2025-12-09
  • Safari Not supported Position: neutral
  • Safari on iOS Not supported Position: neutral

  Baseline availability blocked since December 2025 by Safari (10 months)

• String builtins (WebAssembly)

  Limited availability

  The WebAssembly builtin string functions mirror a subset of the JavaScript String API and adapt it to be efficiently callable without JavaScript glue code.

  Learn more

  • Chrome 130 Released on 2024-10-15
  • Chrome Android 130 Released on 2024-10-15
  • Edge 130 Released on 2024-10-17
  • Firefox 134 Released on 2025-01-07
  • Firefox for Android 134 Released on 2025-01-07
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since January 2025 by Safari (21 months)

• WebDriver BiDi

  Limited availability

  WebDriver BiDi is a bidirectional protocol that allows a WebDriver client and a browser to communicate with each other.

  Learn more

  • Chrome 126 Released on 2024-06-11
  • Chrome Android 126 Released on 2024-06-11
  • Edge 126 Released on 2024-06-13
  • Firefox 117 Released on 2023-08-29
  • Firefox for Android 117 Released on 2023-08-29
  • Safari Not supported Position: support
  • Safari on iOS Not supported Position: support

  Baseline availability blocked since June 2024 by Safari (28 months)

• SharedArrayBuffer in WebGL

  Limited availability

  SharedArrayBuffer objects can be used in WebGL APIs that previously only worked with ArrayBuffer objects.

  Learn more

  • Chrome 60 Released on 2017-07-25
  • Chrome Android 60 Released on 2017-08-01
  • Edge 79 Released on 2020-01-15
  • Firefox 79 Released on 2020-07-28
  • Firefox for Android 79 Released on 2020-07-28
  • Safari Not supported
  • Safari on iOS Not supported

  Baseline availability blocked since July 2020 by Safari (75 months)

• Wheel events

  Limited availability

  The wheel event fires when the user moves a mouse wheel or similar spatially rotating input device.

  Learn more

  • Chrome 31 Released on 2013-11-12
  • Chrome Android 31 Released on 2013-11-14
  • Edge 12 Released on 2015-07-29
  • Firefox 17 Released on 2012-11-20
  • Firefox for Android 17 Released on 2012-11-20
  • Safari 7 Released on 2013-10-22
  • Safari on iOS Not supported

  Baseline availability blocked since July 2015 by Safari (135 months)