DeviceOrientation & DeviceMotion events

API for detecting orientation and motion events from the device running the browser.

Document.execCommand()

Allows running commands to manipulate the contents of an editable region in a document switched to designMode

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.

sandbox attribute for iframes

Method of running external site pages with reduced privileges (e.g. no JavaScript) in iframes.

requestAnimationFrame

API allowing a more efficient way of running script-based animation, compared to traditional methods using timeouts. Also covers support for `cancelAnimationFrame`

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`.

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.

async attribute for external scripts

The boolean async attribute on script elements allows the external JavaScript file to run when it's available, without delaying page load first.

defer attribute for external scripts

The boolean defer attribute on script elements allows the external JavaScript file to run when the DOM is loaded, without delaying page load first.

text-emphasis styling

Method of using small symbols next to each glyph to emphasize a run of text, commonly used in East Asian languages. The `text-emphasis` shorthand, and its `text-emphasis-style` and `text-emphasis-color` longhands, can be used to apply marks to the text. The `text-emphasis-position` property, which inherits separately, allows setting the emphasis marks' position with respect to the text.

Screen Wake Lock API

API to prevent devices from dimming, locking or turning off the screen when the application needs to keep running.

Web Animations API

Lets you create animations that are run in the browser, as well as inspect and manipulate animations created through declarative means like CSS.

Web Workers

Method of running scripts in the background, isolated from the web page

css property: animation-play-state: running

javascript built-in: math: trunc

grammar: trailing commas: trailing comma in dynamic import

javascript operator: `yield*`