Firefoxにおける試験的機能

新しい機能をテストするために、Mozilla は Firefox ブラウザのテスト版である Firefox Nightly を毎日公開しています。提案されたWebプラットフォーム標準の実装など、実験的な機能が利用可能です。このページには、必要に応じて Nightly 版の Firefox の機能と、Firefox の起動方法に関する情報が掲載されています。これらの機能がリリースされる前に、Webサイトとアプリケーションをテストして、最新のWebテクノロジ機能ですべてが機能することを確認できます。

これらの試験的機能をテストするためには、 Firefox Nightly または Firefox Developer Editionをダウンロードしインストールしておくことが必要です。

HTML

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
`<dialog>` Dialog element including DOM APIs to interact with it. Implementation of modal dialogs and accessibility still missing.	Disabled _{(available since 53)}	Disabled _{(available since 53)}	---	---	`dom.dialog_element.enabled`

CSS

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
Subgrids	Disabled	Disabled	Disabled	Disabled	`layout.css.grid-template-subgrid-value.enabled`
Display stray control characters in CSS as hex boxes This feature renders control characters (Unicode category Cc) other than tab (`U+0009`), line feed (`U+000A`), form feed (`U+000C`), and carriage return (`U+000D`) as a hexbox when they are not expected.	43	43	Disabled	Disabled	`layout.css.control-characters.enabled` or `layout.css.control-characters.visible`
Positioned CSS Masks A subset of CSS Masks that includes longhand properties of CSS Masks, as well as a change in the shorthand property	51	51	53	Disabled	Controlled by a compile flag (MOZ_ENABLE_MASK_AS_SHORTHAND).
The `font-variation-settings` property The `font-variation-settings` provides low-level control over OpenType or TrueType font typographic features, by specifying the four letter axis names of the features you want to vary, along with their variation values.	Disabled _{(available since 53)}	Disabled _{(available since 53)}	Disabled _{(available since 53)}	Disabled _{(available since 53)}	`layout.css.font-variations.enabled` Functions only in Mac OS Sierra (and later). For the downloadable fonts on axis-praxis, you also need `gfx.downloadable_fonts.keep_variation_tables` (in Firefox 54 and later)
The `touch-action` CSS property The `touch-action` CSS property is part of the Pointer Events specification and allows you to specify how and in what way the user is able to manipulate an object by touch.	50	—	—	—	`layout.css.touch_action.enabled`
The `shape-outside` CSS property The `shape-outside` (en-US) CSS property is part of the CSS Shapes Module Level 1 specification and allows you to specify a float area causing inline contents to wrap around a shape. Firefox currently implements the `<shape-box>` values (バグ 1309467) as well as the `circle()` (バグ 1311244), `ellipse()` (バグ 1326406), and `polygon()` (バグ 1326409) functions. `shape-outside` (en-US) is animatable since Firefox 57 (バグ 1289049).	Disabled _{(available since 53)}	—	—	—	`layout.css.shape-outside.enabled`
The `contain` CSS property The `contain` CSS property is part of the CSS Containment Module Level 1 specification and allows you to indicate that an element and its contents are independent of the rest of the document tree, allowing user agents to optimize the rendering of a page.	Disabled _{(available since 45)}	Disabled _{(available since 45)}	Disabled _{(available since 45)}	Disabled _{(available since 45)}	`layout.css.contain.enabled`
The `column-span` CSS property The `column-span` CSS property is part of the CSS Multi-column Layout Module specification and allows you to specify how many columns an element spans across. Firefox currently only parses the property (バグ 1339298), it's not actually implemented yet (バグ 616436).	Disabled _{(recognized since 55, but not implemented yet)}	—	—	—	`layout.css.column-span.enabled`
The `frames()` timing function See The frames() class of timing-functions for more details.	Enabled	_N/A	Disabled _{(available since 55)}	Disabled _{(available since 55)}	None

JavaScript

See also ECMAScript Next support for implemented features of ECMAScript 2016 and later, that are not experimental and thus available without preferences in Firefox Release.

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
Additions to the `ArrayBuffer` object Adds the `ArrayBuffer.transfer()` that returns a new `ArrayBuffer` whose contents have been taken from the `oldBuffer`'s data (spec).	36	Disabled	Disabled	Disabled	None
TypedObject objects (spec)	Enabled	Disabled	Disabled	Disabled	None
SIMD (specification and polyfill)	Enabled	Disabled	Disabled	Disabled	None
ECMAScript modules Allows you to use native ECMAScript modules, for example defining modules with `<script type="module">`, defining fallback scripts with `<script nomodule>`, and importing code features that have been exported from modules.	Disabled	Disabled	Disabled	Disabled	`dom.moduleScripts.enabled`

APIs

Canvas & WebGL

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
`WEBGL_debug_renderer_info` extension The `WEBGL_debug_renderer_info` (en-US) extension allows you to transmit information useful to help debugging problems to the server.	42	42	Disabled	Disabled	`webgl.enable-debug-renderer-info`
OffscreenCanvas The `OffscreenCanvas` interface provides a canvas that can be rendered off screen. It is available in both the window and worker contexts.	Disabled _{(available since 44)}	Disabled _{(available since 44)}	Disabled _{(available since 44)}	Disabled _{(available since 44)}	`gfx.offscreencanvas.enabled`
Hit regions Whether the mouse coordinates are within a particular area on the canvas is a common problem to solve. The hit region API allows you define an area of your canvas and provides another possibility to expose interactive content on a canvas to accessibility tools.	Disabled _{(available since 30)}	Disabled _{(available since 30)}	Disabled _{(available since 30)}	Disabled _{(available since 30)}	`canvas.hitregions.enabled`
Streams API Allows JavaScript to programmatically access streams of data received over the network and process them as desired by the developer.	Disabled _{(available since 57)}	Disabled _{(available since 57)}	Disabled _{(available since 57)}	Disabled _{(available since 57)}	`dom.streams.enabled` and `javascript.options.streams`

DOM

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
WebVR API 1.1 on Mac The WebVR API allows you to control and use virtual reality devices.	Enabled	Enabled	Enabled	Disabled	`dom.vr.enabled`
Gamepad extensions The Gamepad Extensions provide access to additional functionality such as pose information in the case of WebVR controllers, and haptic actuator control (e.g. controller vibration hardware).	Enabled	Enabled	Enabled	Disabled	`dom.gamepad-extensions.enabled`
FlyWeb FlyWeb is a project at Mozilla focused on bringing a new set of APIs to the browser for advertising and discovering local-area web servers.	51	Disabled	Disabled	Disabled	`dom.flyweb.enabled`
`HTMLMediaElement.seekToNextFrame()` Part of an experimentation process around support non-real-time access to media for tasks including filtering, editing, and so forth, the `HTMLMediaElement.seekToNextFrame()` (en-US) advances the the current play position to the next frame in the media.	49 _{(Fundamental update in version 50)}	49 _{(Fundamental update in version 50)}	Disabled	Disabled	`media.seekToNextFrame.enabled`
`GeometryUtils.getBoxQuads()` (バグ 917755)	31	31	Disabled	Disabled	`layout.css.getBoxQuads.enabled`
`GeometryUtils.convertPointFromNode()`, `GeometryUtils.RectFromNode()`, and `GeometryUtils.convertQuadFromNode()` (バグ 918189)	31	31	Disabled	Disabled	`layout.css.convertFromNode.enabled`
`Node.rootNode` The `Node.rootNode` (en-US) property returns a `Node` object representing the topmost node in the tree, or the current node if it's the topmost node in the tree. This feature is kept experimental as its naming poses Web compatibility problems. It will be renamed in the future.	48	48	Disabled	Disabled	`dom.node.rootNode.enabled`
WebVTT Regions API WebVTT regions are parts of the video viewport that provide a rendering area for WebVTT cues. The `VTTRegion` is the interface exposing the WebVTT cues. This interface is considered to be in flux and isn't therefore activated in any version by default.	Disabled _{(Experimental implementation since version 30)}	Disabled	Disabled	Disabled	`media.webvtt.regions.enabled`
Support for audio and video tracks Implements `HTMLMediaElement.audioTracks` and `HTMLMediaElement.videoTracks`. Firefox doesn't support multiple audio or video tracks, preventing the most common use cases for these properties to work properly. That's why these properties are not activated by default in any version.	Disabled _{(Experimental implementation since version 33)}	Disabled	Disabled	Disabled	`media.track.enabled`
Better value for `Event.timestamp` The property `Event.timestamp` is returning a `DOMHighResTimeStamp`, which is now relative to the Unix epoch.	32 (Windows) 43 (Linux)	32 (Windows) 43 (Linux)	Disabled	Disabled	`media.track.enabled`
Pointer Events	50	Disabled	Disabled	Disabled	`dom.w3c_pointer_events.enabled`
Pointer Events `PointerEvent.tangentialPressure` and `PointerEvent.twist`	54	Disabled	Disabled	Disabled	`dom.w3c_pointer_events.enabled`
Intersection Observer API The `Intersection Observer API` allows you to configure a callback that is called whenever one item, called a target, intersects either the device viewport or a specified element called.	Disabled _{(available since 53)}	—	—	—	`dom.IntersectionObserver.enabled`
Web Animations API: KeyframeEffect and KeyframeEffectReadOnly The `KeyframeEffectReadOnly.KeyframeEffectReadOnly()` and `KeyframeEffect.KeyframeEffect()` (en-US) constructors can be used to clone existing `KeyframeEffectReadOnly` (en-US) object instances by being given the object to clone as their only parameter (see バグ 1273784.)	52	52	Disabled	Disabled	None
`PromiseRejectionEvent` and related features Providing a way to monitor and more finely control the rejection of Promises.	Disabled _{(available since 55)}	Disabled	Disabled	Disabled	`dom.promise_rejection_events.enabled`
Payment Request API Provides a web API for handling web-based payments.	Disabled _{(available since 55)}	Disabled _{(available since 55)}	Disabled _{(available since 55)}	Disabled _{(available since 55)}	`dom.payments.request.enabled`
Basic Card Payment API Provides dictionaries that define data structures describing card payment types and payment responses for use in the Payment Request API. See `BasicCardRequest` (en-US) and `BasicCardResponse` (en-US).	Disabled _{(available since 56)}	Disabled _{(available since 56)}	Disabled _{(available since 56)}	Disabled _{(available since 56)}	`dom.payments.request.enabled`
The proprietary `Window.content` property is now only available to chrome (privileged) code, and not available to the web anymore (バグ 864845).	Enabled _{(since 57)}	Disabled	Disabled	Disabled

WebRTC

Feature Firefox Nightly Firefox Developer Edition Firefox Beta Firefox Release Preference

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
TCP ICE candidates ICE candidates that use TCP rather than UDP are considered during ICE negotiation.	Disabled 41 Enabled 54	Disabled 41	Disabled 41	Disabled 41	`media.peerconnection.ice.tcp`

TCP ICE candidates
ICE candidates that use TCP rather than UDP are considered during ICE negotiation.

Disabled
41

Enabled
54

Disabled
41

media.peerconnection.ice.tcp

開発者用ツール

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
Debugger rewrite in HTML	52	52	Disabled	Disabled	`devtools.debugger.new-debugger-frontend`
Console rewrite in HTML	52	Disabled	Disabled	Disabled	`devtools.webconsole.new-frontend-enabled`
Experimental Performance tool options Enables options in the UI for JIT optimizations, memory, etc.	41	Disabled	Disabled	Disabled	`devtools.performance.ui.experimental`
Layout side panel The Layout side panel allows to inspect and manage different CSS layout types like CSS Grid Layout.	Disabled _{(available since 52)}	Disabled _{(available since 52)}	Disabled _{(available since 52)}	Disabled _{(available since 52)}	`devtools.layoutview.enabled`

セキュリティ

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
TLS 1.3	Enabled	Enabled	Disabled	Disabled	`security.tls.version.max` to `4`
Blocking data URL navigations on the top-level window We are experimenting with blocking `data:` URLs on the top-level window. See Data URL navigations on top level window will be blocked for a detailed explanation.	Enabled	n/a	Enabled	Disabled	`security.data_uri.block_toplevel _data_uri_navigations`

その他

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
Add to home screen The `icons`, `name`, `short_name`, and `theme_color` fields of the Web App Manifest (if present) can now be as the source of the homescreen/apps window icons, apps window title, homescreen icon title, and apps window color (respectively) for "Add to home screen" (Firefox Mobile only).	Disabled _{(available since 53)}	Disabled _{(available since 53)}	Disabled _{(available since 53)}	Disabled _{(available since 52)}	`manifest.install.enabled`