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

The optional colorSpace parameter of a 2D canvas's getContext() method chooses the color representation, such as "srgb" or "display-p3".

In columnar layouts (created by the columns or column-count CSS properties), the break-after, break-before, break-inside properties control where columns start or end.

Compression Dictionary Transport is a mechanism for using designated HTTP responses as an external dictionary for future HTTP responses for compression schemes that support using external dictionaries (e.g., Brotli and Zstandard)

The Connection-Allowlist HTTP response header limits which requests a page may initiate using fetch and other APIs.

The navigator.contacts API allows you to ask users to share limited details about entries in their contact list with your application.

Container scroll-state queries with the @container scroll-state(...) at-rule apply styles to an element based on the sticky positioning, snapped, and scrollable state of the container.

A container performance entry measures time to render child elements, for container elements that have the containertiming attribute.

The Content Index API allows developers to register their offline enabled content with the browser.

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.

The window.crashReport object is a key-value store to record information about your application's state. If there's a crash, then the data in the key-value store is sent to your crash reporting endpoint, to help you pinpoint the cause of the crash.

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.

The credentialless attribute for the <iframe> HTML element loads third-party content in an ephemeral context and does not send any credentials such as cookies. When using cross-origin isolation, this allows you to embed content that does not send Cross-Origin-Embedder-Policy headers.

The @view-transition CSS rule sets whether a document opts-in to transitions between documents in a multi-page application. Both the old and new document must opt-in for a transition to be triggered.

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

The text-overflow CSS property with a string value sets the string representing clipped text.

The web prefix for ClipboardItem data types (also known as MIME types) allows reading and writing unsanitized custom data from the device clipboard.

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

The @custom-media CSS at-rule names a media query, which you can reuse in multiple @media rules.

The <select> element's appearance, including the button, selected option, picker dropdown, and options, can be customized using CSS.

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

A DOM overlay shows 2D DOM content as an interactive, transparent layer on top of a WebXR application's WebGL content and camera image.

Deprecation reporting sends a report to a URL nominated by the Reporting-Endpoints header or the ReportingObserver API when a page uses a deprecated API or other browser feature.

An XRDepthInformation object represents a measurement of the distance from the user's device to the real-world geometry in the user's environment.

The optional desynchronized parameter of a canvas's getContext() method permits the browser to draw a 2D canvas independently of the event loop. This can reduce drawing latency.

The optional desynchronized parameter of a canvas's getContext() method permits the browser to draw a WebGL canvas independently of the event loop. This can reduce drawing latency.

The optional desynchronized parameter of a canvas's getContext() method permits the browser to draw a WebGL2 canvas independently of the event loop. This can reduce drawing latency.

The device-aspect-ratio, device-height, and device-width media features describe physical properties of the displaying output device.

The navigator.deviceMemory property is the approximate amount of device memory, in gigabytes.

The device posture API and the device-posture CSS media feature reflect the physical posture of a device, such as whether a foldable device is folded or unfolded.