ChildNode.remove()

DOM node method to remove the node itself from the document.

Scoped Styles: the @scope rule

Allows CSS rules to be scoped to part of the document, with upper and lower limits described by selectors.

CSS Filter Effects

Method of applying filter effects using the `filter` property to elements, matching filters available in SVG. Filter functions include blur, brightness, contrast, drop-shadow, grayscale, hue-rotate, invert, opacity, sepia and saturate.

:has() CSS relational pseudo-class

Select elements containing specific content. For example, `a:has(img)` selects all `<a>` elements that contain an `<img>` child.

:in-range and :out-of-range CSS pseudo-classes

If a temporal or number `<input>` has `max` and/or `min` attributes, then `:in-range` matches when the value is within the specified range and `:out-of-range` matches when the value is outside the specified range. If there are no range constraints, then neither pseudo-class matches.

Media Queries: resolution feature

Allows a media query to be set based on the device pixels used per CSS unit. While the standard uses `min`/`max-resolution` for this, some browsers support the older non-standard `device-pixel-ratio` media query.

CSS Reflections

Method of displaying a reflection of an element

CSS Regions

Method of flowing content into multiple elements, allowing magazine-like layouts. While once supported in WebKit-based browsers and Internet Explorer, implementing the feature is no longer being pursued by any browser.

CSS revert value

A CSS keyword value that resets a property's value to the default specified by the browser in its UA stylesheet, as if the webpage had not included any CSS. For example, `display:revert` on a `<div>` would result in `display:block`. This is in contrast to the `initial` value, which is simply defined on a per-property basis, and for `display` would be `inline`.

CSS @when / @else conditional rules

Syntax allowing CSS conditions (like media and support queries) to be written more simply, as well as making it possible to write mutually exclusive rules using `@else` statements.

CSS3 Colors

Method of describing colors using Hue, Saturation and Lightness (hsl()) rather than just RGB, as well as allowing alpha-transparency with rgba() and hsla().

Window.devicePixelRatio

Read-only property that returns the ratio of the (vertical) size of one physical pixel on the current display device to the size of one CSS pixel.

Document Object Model Range

A contiguous range of content in a Document, DocumentFragment or Attr

ECMAScript 2015 (ES6)

Support for the ECMAScript 2015 specification. Features include Promises, Modules, Classes, Template Literals, Arrow Functions, Let and Const, Default Parameters, Generators, Destructuring Assignment, Rest & Spread, Map/Set & WeakMap/WeakSet and many more.

CSS Flexible Box Layout Module

Method of positioning elements in horizontal or vertical stacks. Support includes all properties prefixed with `flex`, as well as `display: flex`, `display: inline-flex`, `align-content`, `align-items`, `align-self`, `justify-content` and `order`.

display: flow-root

The element generates a block container box, and lays out its contents using flow layout. It always establishes a new block formatting context for its contents. It provides a better solution to the most use cases of the "clearfix" hack.

Font unicode-range subsetting

This @font-face descriptor defines the set of Unicode codepoints that may be supported by the font face for which it is declared. The descriptor value is a comma-delimited list of Unicode range (<urange>) values. The union of these ranges defines the set of codepoints that serves as a hint for user agents when deciding whether or not to download a font resource for a given text run.

High Resolution Time API

Method to provide the current time in sub-millisecond resolution and such that it is not subject to system clock skew or adjustments. Called using `performance.now()`

Range input type

Form field type that allows the user to select a value using a slider widget.

Payment Request API

Payment Request is a new API for the open web that makes checkout flows easier, faster and consistent on shopping sites.

relList (DOMTokenList)

Method of easily manipulating rel attribute values on elements, using the DOMTokenList object (similar to classList).

rem (root em) units

Type of unit similar to `em`, but relative only to the root element, not any parent element. Thus compounding does not occur as it does with `em` units.

requestIdleCallback

API allowing the execution of JavaScript to be queued to run in idle browser time, either at the end of a frame or when the user is inactive. Also covers support for `cancelIdleCallback`. The API has similarities with `requestAnimationFrame`.

Ruby annotation

Method of adding pronunciation or other annotations using ruby elements (primarily used in East Asian typography).

display: run-in

If the run-in box contains a block box, same as block. If a block box follows the run-in box, the run-in box becomes the first inline box of the block box. If an inline box follows, the run-in box becomes a block box.

Speech Recognition API

Method to provide speech input in a web browser.

zstd (Zstandard) content-encoding

Data compression method providing faster page loading while using less CPU power on the server.

radionodelist api

range api

range api: detach

range api: setend

rect api

rect api: bottom

rect api: left

rect api: right

rect api: top

remoteplayback api

request api

request api: blob

request api: body

request api: cache

request api: json

request api: mode

request api: text

response api

response api: blob

response api: json

response api: ok

response api: type

css property: r