The popover="hint" global HTML attribute creates a popover that is subordinate to popovers with a popover="auto" attribute. You can use this to create tooltips that don't dismiss auto popovers.

The ruby-overhang CSS property sets whether ruby annotations may overlap adjacent text.

The getAllRecords() method of IDBObjectStore and IDBIndex return records and their primary keys from an IndexedDB store or index. The records can be read in batches and in reverse order. The getAllRecords() methods speed up read operations on large datasets.

The picture-in-picture API allow websites to create a floating, always-on-top video window. Also known as PiP or pop-out video.

The named-feature() function, when used with @supports, checks if a named CSS behavior is supported. The CSS behavior names are defined by specification. For example, @supports named-feature(anchor-position-follows-transforms) checks whether anchor-positioning applies after transforms."

The <template for="…"> HTML element replaces the content at a named range or insertion point, marked by the processing instructions <?start name="…"> and <?end> or <?marker name="…">. You can use this to stream or "patch" partial updates into the document out of order.

The flex-wrap: balance CSS declaration distributes items in a multi-line flex container such that each line has about the same number of items.

An HTML processing instruction is text enclosed by <? and >, which marks a target for further processing. They may appear anywhere in a document. They are ignored like comments when they're not recognized for a specific purpose.

The scroll(), scrollBy(), scrollTo(), and scrollIntoView() methods on the Element and Window interfaces return Promises that resolve when scrolling completes.

The text-fit CSS property scales text to fill the inline size of its container. You can use this to grow or shrink headlines, captions, or pull quotes to fit a container.

The url() CSS function accepts a cross-origin() modifier to control cross-origin resource sharing (CORS) when requesting the URL. For example, url("https://example.com" cross-origin(anonymous))) does not send credentials to the URL.

The url() CSS function accepts an integrity() modifier to use subresource integrity to verify the response from the requested URL.

The url() CSS function accepts a referrer-policy() modifier to choose which referrer to send when requesting the URL. For example, `url("https://example.com" referrer-policy(no-referrer)) does not send a referrer to the URL.

The loading="lazy" attribute for <video> and <audio> elements defers loading the media resource until the element is near the viewport. This matches the lazy-loading behavior for <img> and <iframe> elements.

The background-clip: border-area CSS declaration draws the background underneath only the border of an element.

The AccentColor and AccentColorText CSS system color values are the background color and text color of accented user interface controls. To prevent browser fingerprinting, browsers may (and often do) use fixed color values that do not reflect user customization or theming choices.

A CSSPseudoElement object represents a pseudo-element and its context in the document tree. You get an instance through the pseudo() method of Element or CSSPseudoElement objects or the pseudoTarget property of some events.

The migrate_to and migrate_from web app manifest members move an installed app from one origin to another, within the same site. They preserve the user's installation settings on the device, like shortcuts.

The column-rule and row-rule CSS properties display decorative lines between columns and rows of a flex, grid, or multi-column layout. The rule-break, rule-outset, and rule-paint-order properties control the appearance of these lines.

The document picture-in-picture API creates an always-on-top window from arbitrary HTML content.

The navigator.serial API communicates with devices over serial ports, such as microcontrollers.

An Origin object represents an origin, as in a scheme, hostname, and port. You can use it to make same-site and same-origin comparisons.

The hanging-punctuation CSS property puts punctuation characters outside of the box to align the text with the rest of the document.

The extendedLifetime option of the SharedWorker() constructor gives shared workers extra time to perform operations after all pages using it have been navigated away from or closed.

The LanguageDetector API identifies the likely natural language that some text is written in. You can use this API to supplement machine translation when the source source language is not known.

The Translator API translates some text from one natural language to another, using machine translation.

The LanguageModel API prompts an on-device language model. Also known as the Prompt API.

The CSS.highlights.highlightsFromPoint() method returns an array of Highlight objects at a specified point.

The sizes="auto" attribute for the <img> HTML element sets the layout size for the image based on the computed layout size when choosing a source from the srcset. This attribute only applies to images with the loading="lazy" attribute.

The overscroll-behavior CSS property disables default scrolling behaviors when the edges of a scrolling area are reached.