Experimental features in Firefox

Mozilla 发布了测试的 nightly 版本，用于测试新的浏览器特性。实验性特性，例如所提议的可用的 Web 平台标准的实现。这个页面列出了 Firefox Nightly 中的一些新特性和启用方法等信息。在发布这些功能之前，你可以测试 Web 站点和应用程序，并确保一切都能与最新的 Web 技术功能协同工作。

你需要下载隔夜版或是开发者版，来测试下面这些实验性特性。

HTML

功能	Firefox Nightly	Firefox 开发者版	Firefox 测试版	Firefox 发行版	Preference
日期和时间输入`<input>`为日期和时间相关的输入类型提供的新用户界面	开启 _{(从 51 开始支持，从 55 开始默认开启)}	开启 _{(从 51 开始支持)}	关闭 _{(从 51 开始支持)}	---	`dom.forms.datetime`
`<dialog>` 包含与之交互的 DOM 元素的对话框元素。Implementation of modal dialogs and accessibility still missing.	关闭 _{(从 53 开始支持)}	关闭 _{(从 53 开始支持)}	---	---	`dom.dialog_element.enabled`

CSS

功能	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 (en-US), 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-display` descriptor for `@font-face` To improve Web fonts performance, `@font-face` has an experimental `font-display` descriptor.	关闭 _{(available since 46)}	关闭 _{(available since 46)}	关闭 _{(available since 46)}	关闭 _{(available since 46)}	`layout.css.font-display.enabled`
`font-variation-settings` 属性 `font-variation-settings` 提供了 OpenType 或 TrueType 字体印刷特点的低级别的控制，by specifying the four letter axis names of the features you want to vary, along with their variation values.	关闭 _{(available since 53)}	关闭 _{(available since 53)}	关闭 _{(available since 53)}	关闭 _{(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)
`touch-action` CSS 属性 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` 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 (Firefox bug 1309467) as well as the `circle()` (Firefox bug 1311244), `ellipse()` (Firefox bug 1326406), and `polygon()` (Firefox bug 1326409) functions.	关闭 _{(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.	关闭 _{(available since 45)}	关闭 _{(available since 45)}	关闭 _{(available since 45)}	关闭 _{(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 (Firefox bug 1339298), it's not actually implemented yet (Firefox bug 616436).	关闭 _{(recognized since 55, but not implemented yet)}	—	—	—	`layout.css.column-span.enabled`
The `frames()` timing function See The frames() class of timing-functions (en-US) for more details.	开启	_N/A	关闭 _{(available since 55)}	关闭 _{(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`

DOM

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
Mac 上的 WebVR API 1.1 WebVR API 允许你控制并和使用虚拟现实设备。	Enabled	Disabled	Disabled	Disabled	`dom.vr.enabled`
游戏手柄扩展 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`
Experimental fetch controller/signal/observer interfaces Also known as "cancellable fetch", these interfaces contain functionality to allow fetch request operations to be observed and controlled during their lifetimes.	Disabled _{(Available since 55)}	Disabled	Disabled	Disabled	`dom.fetchObserver.enabled` and `dom.fetchController.enabled` (not in `about:config` by default; you must set them yourself).
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()` (Firefox bug 917755)	31	31	Disabled	Disabled	`layout.css.getBoxQuads.enabled`
`GeometryUtils.convertPointFromNode()`, `GeometryUtils.RectFromNode()`, and `GeometryUtils.convertQuadFromNode()` (Firefox bug 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`
Performance Observer API The `PerformanceObserver` interface is used to observe performance measurement events and be notified of new performance entries as they are recorded in the browser's performance timeline.	49	Disabled	Disabled	Disabled	`dom.enable_performance_observer`
WebVTT Regions API WebVTT (en-US) regions are parts of the video viewport that provide a rendering area for WebVTT cues. The `VTTRegion` (en-US) 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`
音频和视频轨道支持 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`
指针事件	50	Disabled	Disabled	Disabled	`dom.w3c_pointer_events.enabled`
Pointer Events `PointerEvent.tangentialPressure` (en-US) and `PointerEvent.twist` (en-US)	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 Firefox bug 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 为网络支付提供的一个 API。	Disabled _{(available since 55)}	Disabled _{(available since 55)}	Disabled _{(available since 55)}	Disabled _{(available since 55)}	`dom.payments.request.enabled`

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

开发者工具

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`

其他

Feature	Firefox Nightly	Firefox Developer Edition	Firefox Beta	Firefox Release	Preference
添加到主屏幕 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).	关闭 _{(available since 53)}	关闭 _{(available since 53)}	关闭 _{(available since 53)}	关闭 _{(available since 52)}	`manifest.install.enabled`
TLS 1.3	开启	开启	关闭	关闭	`security.tls.version.max` to `4`