Blob URLs

Method of creating URL handles to the specified File or Blob object.

ch (character) unit

Unit representing the width of the character "0" in the current font, of particular use in combination with monospace fonts.

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.

Data URIs

Method of embedding images and other files in webpages as a string of text, generally using base64 encoding.

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`.

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.

Fullscreen API

API for allowing content (like a video or canvas element) to take up the entire screen.

Color input type

Form field allowing the user to select a color.

querySelector/querySelectorAll

Method of accessing DOM elements using CSS selectors

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.

SVG (basic support)

Method of displaying basic Vector Graphics features using the embed or object elements. Refers to the SVG 1.1 spec.

FIDO U2F API

JavaScript API to interact with Universal Second Factor (U2F) devices. This allows users to log into sites more securely using two-factor authentication with a USB dongle.

unhandledrejection/rejectionhandled events

The `unhandledrejection` event is fired when a Promise is rejected but there is no rejection handler to deal with the rejection. The `rejectionhandled` event is fired when a Promise is rejected, and after the rejection is handled by the promise's rejection handling code.

URL API

API to retrieve the various parts that make up a given URL from a given URL string.

URL Scroll-To-Text Fragment

URL fragment that defines a piece of text to be scrolled into view and highlighted.

URLSearchParams

The URLSearchParams interface defines utility methods to work with the query string of a URL.

CSS user-select: none

Method of preventing text/element selection using CSS.

User Timing API

Method to help web developers measure the performance of their applications by giving them access to high precision timestamps.

Small, Large, and Dynamic viewport units

Viewport units similar to `vw` and `vh` that are based on shown or hidden browser UI states to address shortcomings of the original units. Currently defined as the `sv*` units (`svb`, `svh`, `svi`, `svmax`, `svmin`, `svw`), `lv*` units (`lvb`, `lvh`, `lvi`, `lvmax`, `lvmin`, `lvw`), `dv*` units (`dvb`, `dvh`, `dvi`, `dvmax`, `dvmin`, `dvw`) and the logical `vi`/`vb` units.

Viewport units: vw, vh, vmin, vmax

Length units representing a percentage of the current viewport dimensions: width (vw), height (vh), the smaller of the two (vmin), or the larger of the two (vmax).

CSS -webkit-user-drag property

The non-standard `-webkit-user-drag` CSS property can be used to either make an element draggable or explicitly non-draggable (like links and images). See the standardized [draggable attribute/property](/mdn-api_htmlelement_draggable) for the recommended alternative method of accomplishing the same functionality.

types: `<length>`: `vi` unit

html element: u

html element: ul

javascript operator: unary negation (`-`)

javascript operator: bitwise unsigned right shift (`a >>> b`)

uc browser for android