The window.external.AddSearchProvider() and window.external.IsSearchProviderInstalled() do nothing. Historically, they added external search providers to the browser.

The font-variant-position CSS property sets whether to use alternate glyphs for subscript and superscript text.

The audioTracks and videoTracks APIs for media elements switch audio and video tracks during playback.

The fastSeek() method seeks an <audio> or <video> element as fast as possible, by seeking to a keyframe instead of exactly the requested time.

The playback of multiple <video> or <audio> elements can be coordinated by a MediaController instance, for example to synchronize a sign-language interpreter track with the main video track.

The WEBGL_compressed_texture_pvrtc extension for WebGL 1.0 and 2.0 contexts adds PVRTC compressed texture formats to compressedTexImage2D() and compressedTexSubImage2D().

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

The rel="alternate stylesheet" attribute for the <link> HTML element offers an alternative style option to users.

The ime-mode CSS property sets the state of the input method editor for text fields.

The glyph-orientation-vertical CSS property sets the orientation of glyphs in text rendered in a vertical writing mode.

The :target-within CSS pseudo-class matches the element with an ID matching the URL fragment and its ancestors.

The <install> HTML element represents a button that, upon activation, prompts the user to choose whether to install a progressive web app.

The <usermedia> HTML element represents a button that, upon activation, toggles camera or microphone streams. If needed, it may prompt the user to choose whether to grant the page access to the camera and microphone.

The @mixin and @apply CSS at-rules define reusable style declaration fragments and apply them inside rules, optionally passing arguments.

The Ad Selection API facilitates advertisement sales by allowing sites to register users as part of an interest group or to choose which ads appear based on those interest groups, while minimizing the ability of advertisers to track specific members of the interest group.

The AmbientLightSensor API returns the current light level in lux of the ambient light level around the device.

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

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

Device-bound session credentials is a protocol to request proof of possession of a private key. Regularly confirming key possession can help protect against cookie theft.

The EXT_disjoint_timer_query extension for WebGL 1.0 contexts measures the duration of a set of GL commands, without stalling the rendering pipeline.

The toolname, tooldescription, and toolautosubmit HTML form element attributes register actions that can be called by in-browser AI agents or browser extensions. Also known as declarative WebMCP.

A <canvas> HTML element with the layoutsubtree attribute can draw descendant elements in its rendering context. You can use it to style and layout text in a canvas, expose canvas content to browser features (like accessibility, translate, or find-in-page), and apply 2D and 3D effects to HTML.

The setHTML(), replaceWithHTML(), beforeHTML(), prependHTML(), appendHTML() and afterHTML() DOM methods, and unsafe equivalents, insert HTML into an existing tree.

The streamHTML(), streamReplaceWithHTML(), streamBeforeHTML(), streamPrependHTML(), streamAppendHTML() and streamAfterHTML() DOM methods, and unsafe equivalents, return writeable streams that incrementally insert HTML into an existing tree.

The headingoffset HTML attribute offsets the heading level of descendant <h1>–<h6> elements. The headingreset HTML attribute prevents heading offset computation from traversing beyond the element.

The :heading and :heading() CSS pseudo-classes match headings of varying levels. The :heading pseudo-class matches any heading (<h1> through <h6>). The :heading() selector matches any of the given levels. For example, :heading(1, 2) matches headings level 1 and 2.

Module import … assert { type: "json" } and import … assert { type: "css" } JavaScript statements load JSON and CSS data.

Subresource integrity violation reporting sends a report to a URL nominated by the Reporting-Endpoints header or the ReportingObserver API when a resource request violates an integrity check.

The link-parameters CSS property, param() modifier for the url() CSS function, and the #:~:param(…) URL fragment set custom CSS environment variables on an external resource, such as an SVG image, allowing the external resource to adapt its presentation based on the variables.

The Magnetometer API reads magnetic field sensor data from the device's magnetometer.