The font-family: math CSS declaration uses the browser default font face for displaying mathematical expressions.

The WebTransport API transmits data between a client and a server, by using the HTTP/3 protocol.

The Reporting-Endpoints HTTP header and ReportingObserver() API send selected reports, such as Content Security Policy (CSP) violation reports or crash reports, to a nominated URL or callback function.

The text-indent: each-line CSS declaration indents text after forced breaks as well as to the first line of a block.

The text-indent: hanging CSS declaration indents all lines except the first.

Branch hints in WebAssembly allows a browser to optimize performance when a branch is a likely to take a specific path.

The shape() CSS function creates shapes with a series of commands like line, move, and curve. It can be used with clip-path and shape-outside.

Trusted types allow you to lock down insecure parts of the DOM API and prevent client-side cross-site scripting (XSS) attacks.

The getOrInsert() and getOrInsertComputed() methods of Map objects get a value, setting and getting a default value if needed.

Zstandard or zstd is a fast lossless compression algorithm. When used as a content encoding, it is often faster and offers better compression than brotli.

The rcap CSS length unit is a font-relative length equal to the value of the cap unit on the root element. Cap-height is approximately equal to the height of a capital Latin letter.

The rch CSS length unit is a font-relative length equal to the value of the ch unit on the root element. ch length is based on the width of the zero (0) character.

The rex CSS length unit is a font-relative length that is equal to the x-height of the root element.

The ric CSS length unit, or root international character, is a font-relative length equal to the width of CJK character relative to the root element.

The :active-view-transition CSS pseudo-class matches the root element when a view transition is active. The :active-view-transition-type() CSS pseudo-class matches only when the active view transition was started with the specified type.

The navigator.serviceWorker.register() method accepts { type: "module" } to load scripts that use import and export. Also known as ECMAScript modules or ESM in service workers.

The navigation API initiates, intercepts, or modifies browser navigation actions. Not to be confused with the navigator API.

The text-decoration-line: spelling-error and text-decoration-line: grammar-error CSS declarations apply the browser's marking for spelling and grammatical mistakes. This is typically a wavy underline in red or green.

The command and commandfor attributes for the <button> HTML element dispatch an action to an element when the button is invoked (by click or keystroke), as a declarative alternative to addEventListener() calls or onclick attribute handlers.

The document.caretPositionFromPoint() method finds an insertion point, represented by a DOM node and an offset within that node, for given coordinates in the viewport.

The scrollbar-color CSS property sets the color of the scrollbar track and thumb.

The scrollend event fires when an element or document has finished scrolling.

An event or first-input performance entry measures the latency of user input events, such as mouse clicks or keypresses. They're used to calculate interaction to next paint (INP), a common metric for perceived responsiveness.

A largest-contentful-paint performance entry measures the time it takes for the largest image or text to appear. Largest contentful paint (LCP) is a common metric for perceived loading times.

The Atomics.waitAsync() static method waits for a value in a shared memory location, providing a promise when the expected value is not yet in memory. The waitAsync() method is a non-blocking alternative to Atomics.wait().

The view-transition-class CSS property sets a name that can be used to apply styles to multiple named view transition pseudo-elements.

View transitions allow you to create animated visual transitions between different states of a document.

The WebRTC encoded transform API allows you to modify audio and video streams in WebRTC connections. For example, it can be used for visual effects or custom codecs.

The ::details-content pseudo-element selects the expandable content of a <details> element, excluding the <summary>.

The rel="dns-prefetch" attribute for the <link> HTML element is a hint to the browser that the page or user is likely to request resources from another domain, so the browser should preemptively resolve DNS for the href value's domain.