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.

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.

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.

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.

Dispatches selectionchange event per element when this element(input/textarea) provides a text selection or its selection changes. This is to match the latest specification of selectionchange event. This also matches Safari behavior.

Reconciles the FedCM and Storage Access APIs by making a prior FedCM grant a valid reason to automatically approve a storage access request. When a user grants permission for using their identity with a 3rd party Identity Provider (IdP) on a Relying Party (RP), many IdPs require third-party cookies to function correctly and securely. This proposal aims to satisfy that requirement in a private and secure manner by updating the Storage Access API (SAA) permission checks to not only accept the permission grant that is given by a storage access prompt, but also the permission grant that is given by a FedCM prompt. A key property of this mechanism is limiting the grant to cases explicitly allowed by the RP via the FedCM permissions policy, enforcing a per-frame control for the RP and preventing passive surveillance by the IdP beyond the capabilities that FedCM already grants, as outlined in the Privacy Considerations.

Font-variant-emoji CSS property provides users an easy way to control between colored (emoji-style) and monochromatic (text-style) emoji glyphs presentations. This can be also done by adding an emoji Variation Selector, specifically U+FE0E for text and U+FE0F for emojis, after each emoji codepoint. Using font-variant-emoji CSS property allows web developers to select between emoji style (colored) emoji presentation, text style (monochromatic) emoji presentation and unicode default emoji presentation [0]. This property only affects emojis that are part of a Unicode emoji presentation sequence [1]. [0] https://www.unicode.org/reports/tr51/tr51-25.html#Emoji_Presentation [1] http://www.unicode.org/emoji/charts/emoji-variants.html

Imported ES modules can't currently have their integrity checked, and hence cannot run in environments that require Subresource Integrity or with `require-sri-for` CSP directives. This feature adds an `integrity` section to import maps, enabling developers to map ES module URLs to their integrity metadata, and ensure they only load when they match their expected hashes.

Modifies the Private Aggregation API to add a 'filtering ID' to the aggregatable reports' encrypted payloads. This ID allows histogram contributions with different filtering IDs to be processed separately on the aggregation service. A list of filtering IDs could be provided in an aggregation query and any contributions not matching a listed ID will be filtered out, not contributing to the result. To support the new feature, we update the report version to "1.0" (from "0.1"). By the time this is launched to Stable, all valid aggregation service releases will support the new report version, avoiding backwards compatibility concerns. (Old releases are deprecated on a regular schedule.)

Line-breaks are possible within elements with `display: ruby`. A single pair of a ruby-base and a ruby-text has never been line-breakable, and it has been pushed to the next line if the current line had no enough space for the entire pair. Now each of the ruby-base and the ruby-text can be split into multiple lines.