Experimental Chromium Web Platform Features

A JavaScript API for detecting the language of text, with confidence levels.

With this change <meter> elements with `appearance: none` will have a reasonable fallback style that matches Safari and Firefox instead of just disappearing from the page. As well developers will be able to custom style the <meter> elements. A feature flag MeterAppearanceNoneFallbackStyle is available until Chrome 133 to control this feature.

Many applications have multiple media flows of the same data type and often some of the flows are more important than others. The priority setting can be used to indicate the relative priority of various flows. The priority API allows the JavaScript applications to tell the browser whether a particular media flow is high, medium, low or of very low importance to the application.

This API allows processing of encoded media flowing through an RTCPeerConnection. Chromium shipped an early version of this API in 2020. Since then, the spec has changed and other browsers have shipped the updated version of the spec (Safari in 2022 and Firefox in 2023). This launch refers to the latest spec version.

Support of `sideways-rl` and `sideways-lr` keywords for `writing-mode` CSS property is added. They are vertical writing modes, and all letters are sideways.

The RTCDataChannel interface is part of the WebRTC standard, and represents a network channel which can be used for bidirectional peer-to-peer transfers of arbitrary data. This feature tracks exposing RTCDataChannel in dedicated workers, and allowing the transfer of RTCDataChannels to them workers. This will help reduce main thread contention and lead to smoother and more reliable WebRTC applications.

Support box-decoration-break:clone both for inline fragmentation (line layout) and block fragmentation (pagination for printing, multicol). Traditionally in Blink, only box-decoration-break:slice (the initial value) has been supported for block fragmentation, whereas for inline fragmentation, box-decoration-break:clone was also supported, but only when using the prefixed -webkit-box-decoration-break property. See https://drafts.csswg.org/css-break/#break-decoration

This feature is not to fire selectionchange event when there is already one pending. For web developers, selectionchange event listeners will be called less often with this feature. Before this feature, every time the mutation of the selection on one target(input/textarea/document) would make the listener to be called once. Now with this feature, before the selectionchange event listner is finally called, multiple mutations of the selection on one target would make the listener to be called only once.

Adds a Controlled Frame API available only to Isolated Web Apps (IWAs). This work will add a new Controlled Frame API which is only available to Isolated Web Apps (IWAs). Like similarly-named APIs on other platforms, Controlled Frame allows embedding all content, even third party content that can't be embedded in <iframe>. Controlled Frame also allows controlling embedded content with a collection of API methods and events. For more info on Isolated Web Apps, see the IWA explainer: https://github.com/WICG/isolated-web-apps/blob/main/README.md

Replaces the inset-area() function with inset-area values directly within position-try-fallbacks. This means that you now just write e.g. position-try-fallbacks:top instead of position-try-fallbacks:inset-area(top).

The reading-flow CSS property controls the order in which elements in a flex or grid layout are rendered to speech or are navigated to when using (linear) sequential navigation methods. This feature implements the listed values: * normal * flex-visual * flex-flow * grid-rows * grid-columns * grid-order

This feature allows scrollIntoView with behavior: "smooth" to run concurrently on scroll containers which are neither descendants nor ancestors of one another. scrollIntoView with behavior: "smooth" is a JavaScript method developers can use to cause scroll containers to scroll to their descendants via a gentle scroll animation. This feature fixes Chrome's implementation of the API so that ongoing scrollIntoView animations are not cancelled by unrelated scrolls on other scroll containers. This codepen[1] demonstrates the difference in behavior between Chrome and other browsers. The features also fixes cases where Chrome fails to scroll to a page's fragment anchor because of a competing scrollIntoView that is invoked when the page loads. [1] https://codepen.io/awogbemila/pen/GRaJQMG

Add support for page margin boxes, when printing a web document, or exporting it as PDF. @page margin boxes allows an author to define the contents in the margin area of a page, for instance to provide custom headers and footers, rather than using the built-in headers and footers generated by the browser. A margin box is defined via an at-rule inside a CSS @page rule. There are 16 rules defined, one for each page margin box. There's one margin box for each of the 4 corners on the page, and three (start, middle, end) for each of the 4 sides. The appearance and the contents of a margin box are specified with CSS properties inside the at-rule, including the "content" property. Counters are also to be supported, for page numbering. The specification defines two special counter names: "page" for the current page number, and "pages" for the total number of pages.

This change makes the HTML parser allow additional tags in <select> besides <option>, <optgroup>, and <hr>. This change is in support of the customizable <select> feature but is being shipped first because it can be done separately and has some compat risk which I'd like to get feedback on. This feature is gated by the temporary policy (SelectParserRelaxationEnabled). This is a temporary transition period, and the policy will stop working on milestone M136 Customizable select explainer: https://open-ui.org/components/customizableselect/ I did a compat analysis and determined that the vast majority of sites which would see the effects of the parser changes would not have their behavior changed. More details here: https://github.com/whatwg/html/issues/10310 If there are major issues with this change, I will reassess and make adjustments to the parser as needed.

Adds tone mapping parameters to the WebGPU canvas configuration, and adds options of "standard" (the current behavior of restricting content to the SDR range of the display) as the default, and "extended" (not imposing this restriction) as a new behavior. This allows WebGPU content to use the full range of a display.

Websites can and do get credentials from mobile wallet apps through a variety of mechanisms today (custom URL handlers, QR code scanning, etc.). This Web Platform feature would allow sites to request identity information from wallets via Android's IdentityCredential CredMan system. It is extensible to support multiple credential formats (eg. ISO mDoc and W3C verifiable credential) and allows multiple wallet apps to be used. Mechanisms are being added to help reduce the risk of ecosystem-scale abuse of real-world identity (see https://docs.google.com/document/u/1/d/1L68tmNXCQXucsCV8eS8CBd_F9FZ6TNwKNOaFkA8RfwI/edit).

AudioContext creation and audio rendering errors are reported to web applications via a callback assigned to AudioContext.onerror.

The AudioContext.playoutStats API allows an application to measure the quality and latency of audio playout using WebAudio.

Allow WebAuthn relying parties to report information about existing credentials back to credential storage providers, so that incorrect or revoked credentials can be updated or removed from provider and system UI. https://github.com/w3c/webauthn/wiki/Explainer:-WebAuthn-Signal-API-explainer

The anchor-scope property allows limiting the visibility of anchor names to a given subtree.

Support of new CSS property `ruby-align` is added. The property accepts one of `space-around` `space-between` `start` and `center` keywords, and controls alignment of ruby base text and ruby annotation text.

Snap Events allow developers reliably listen for when the "snap target" of a scroller changes and perform style adjustments as desired. CSS scroll snap points are often used as a mechanism to create scroll interactive "selection" components, where selection is determined with javascript intersection observers and a scroll end guestimate. By creating built-in events, the invisible state will become actionable, at the right time, and always correct. This feature adds two JavaScript events: scrollsnapchange and scrollsnapchanging. Scrollsnapchange lets developers know, at the completion of a scroll operation (including snapping), that the element to which a scroller is snapped has changed. Scrollsnapchanging gives developers a hint, during a scroll operation, that the user agent intends to snap the scroll container to a new snap target based on the scrolling input so far.

Snap Events allow developers reliably listen for when the "snap target" of a scroller changes and perform style adjustments as desired. CSS scroll snap points are often used as a mechanism to create scroll interactive "selection" components, where selection is determined with javascript intersection observers and a scroll end guestimate. By creating built-in events, the invisible state will become actionable, at the right time, and always correct. This feature adds two JavaScript events: scrollsnapchange and scrollsnapchanging. Scrollsnapchange lets developers know, at the completion of a scroll operation (including snapping), that the element to which a scroller is snapped has changed. Scrollsnapchanging gives developers a hint, during a scroll operation, that the user agent intends to snap the scroll container to a new snap target based on the scrolling input so far.