EventTarget.addEventListener()

The modern standard API for adding DOM event handlers. Introduced in the DOM Level 2 Events spec. Also implies support for `removeEventListener`, the [capture phase](https://dom.spec.whatwg.org/#dom-event-capturing_phase) of DOM event dispatch, as well as the `stopPropagation()` and `preventDefault()` event methods.

EOT - Embedded OpenType fonts

Type of font that can be derived from a regular font, allowing small files and legal use of high-quality fonts. Usage is restricted by the file being tied to the website

hidden attribute

The `hidden` attribute may be applied to any element, and effectively hides elements similar to `display: none` in CSS.

IndexedDB

Method of storing data client-side, allows indexed database queries.

IndexedDB 2.0

Improvements to Indexed DB, including getAll(), renaming stores and indexes, and binary keys.

Path2D

Allows path objects to be declared on 2D canvas surfaces

html element: address

html element: dd

javascript built-in: atomics: add

javascript built-in: set: add

javascript built-in: temporal api: zoneddatetime

javascript built-in: temporal api: zoneddatetime: add

javascript built-in: temporal api: zoneddatetime: calendarid

javascript built-in: temporal api: zoneddatetime: compare

javascript built-in: temporal api: zoneddatetime: day

javascript built-in: temporal api: zoneddatetime: dayofweek

javascript built-in: temporal api: zoneddatetime: dayofyear

javascript built-in: temporal api: zoneddatetime: daysinweek

javascript built-in: temporal api: zoneddatetime: daysinyear

javascript built-in: temporal api: zoneddatetime: equals

javascript built-in: temporal api: zoneddatetime: era

javascript built-in: temporal api: zoneddatetime: erayear

javascript built-in: temporal api: zoneddatetime: from

javascript built-in: temporal api: zoneddatetime: hour

javascript built-in: temporal api: zoneddatetime: hoursinday

javascript built-in: temporal api: zoneddatetime: inleapyear

javascript built-in: temporal api: zoneddatetime: minute

javascript built-in: temporal api: zoneddatetime: month

javascript built-in: temporal api: zoneddatetime: monthcode

javascript built-in: temporal api: zoneddatetime: nanosecond

javascript built-in: temporal api: zoneddatetime: offset

javascript built-in: temporal api: zoneddatetime: round

javascript built-in: temporal api: zoneddatetime: second

javascript built-in: temporal api: zoneddatetime: since

javascript built-in: temporal api: zoneddatetime: startofday

javascript built-in: temporal api: zoneddatetime: subtract

javascript built-in: temporal api: zoneddatetime: timezoneid

javascript built-in: temporal api: zoneddatetime: toinstant

javascript built-in: temporal api: zoneddatetime: tojson

javascript built-in: temporal api: zoneddatetime: tostring

javascript built-in: temporal api: zoneddatetime: until

javascript built-in: temporal api: zoneddatetime: valueof

javascript built-in: temporal api: zoneddatetime: with

javascript built-in: temporal api: zoneddatetime: year

javascript built-in: weakset: add

javascript operator: addition (`+`)