Limited Availability
28 featuresMathML specifies several elements and attributes that are not included in MathML Core. Math applications outside of browsers may implement these features, but they are discouraged for web use.
Mutation events like DOMSubtreeModified, DOMNodeInserted, or DOMNodeRemoved fire when DOM changes occur.
The createValueRange() for form elements, such as <textarea> or <input type="text">, gets an OpaqueRange object that represents a live span of text. You can use this for range-based operations on the input text, such as setting custom highlights or placing autocomplete popovers.
The <portal> HTML element embeds another page into the current page as a non-interactive preview.
The Access-Control-Request-Private-Network: true and Access-Control-Allow-Private-Network: true HTTP request and response headers establish permission for websites to make requests to internal networks, such as to routers.
The frame-sizing CSS property sets the size of an <iframe> element to that of it contents, to avoid scrolling in the iframe. Embedded documents allow this with the <meta name="responsive-embedded-sizing"> element and request resizing in the embedding page by calling window.requestResize().
The line-height-step CSS property creates consistent vertical rhythm by setting the spacing between body text baselines. It rounds taller lines like headings up to the next multiple of the body text spacing.
The SpeechRecognition.grammars property of the Web Speech API represents a set of words or patterns of words that the recognition service should recognize, used for when the recognition service's accuracy is low.
Attributes and properties of table elements, such as align, vAlign, noWrap, bgcolor, or char set various visual presentation properties of the table and its sections and cells.
The topics API reports a user's likely subject-matter interests (as determined by the browser, known as topics) to iframes. This allows for interest-based advertising that does not rely on user's exact browsing history, third-party cookies, or fingerprinting.
The cancel() method of a TransformStream transformer cleans up resources when the readable side cancels or the writable side aborts.
The _localized suffixed members of the web app manifest set translated names, descriptions, icons, and shortcuts. The browser automatically selects resources based on the user's language and region settings.
The WebNN API constructs and executes computational graphs of neural networks by making use of the various machine learning capabilities and hardware accelerators available on the device. Also known as Web Neural Network API.
The navigator.getVRDisplays() API represents virtual reality (VR) devices, including sensors and head-mounted displays.
The color-contrast() CSS function picks a color from a list that has the most contrast with another color.
The display: contents CSS declaration sets an element to display only its contents, not itself.
The document.modelContext API registers page actions that can be called by in-browser AI agents or browser extensions. Also known as WebMCP.
The element() CSS function creates a live-updating image from an HTML element that can be used as an image or background image.
The fit-content() CSS function, used outside of a grid layout property, clamps a length between min-content and max-content.
The focusgroup global HTML attribute combines descendant elements into a single tab stop, with arrow-key navigation between them, for toolbars, tabs, menus, radio groups, and other composite controls. It's an alternative to the sequential navigation of tabindex.
The getBoxQuads() method, when called on a document, element, pseudo-element, or text node, returns the list of DOMQuad objects that represent the CSS boxes used to render the node.
The image() CSS function creates an image similar to url() but with additional functionality. It can create a solid color as an image, provide a fallback from an image URL to a solid color, or clip a sprite image using media fragments. Not to be confused with the Image() constructor.
The import defer JavaScript statement imports a module while deferring its evaluation until its first use.
The line-clamp CSS property limits the text in a block container to a certain number of lines. The prefixed -webkit-line-clamp is widely supported but only works with -webkit-box-orient: vertical in combination with display: -webkit-box or display: -webkit-inline-box.
The prefers-reduced-data CSS media query detects whether the user has a preference for using less network traffic. For example, you can use this media query to avoid loading large font files and use a system font instead.