The Document Object Model (DOM) is a programming interface for HTML, XML and SVG documents.
The Web Animations API allows for synchronizing and timing changes to the presentation of a Web page, i.e. animation of DOM elements. It does so by combining two models: the Timing Model and the Animation Model.
The Battery Status API, more often referred to as the Battery API, provides information about the system's battery charge level and lets you be notified by events that are sent when the battery level or charging status change.
The Camera API allows applications to manage the camera of the device. It allows them to take photographs, record videos, and get information like the focus, the zoom, the white balance, the flash, … It is a priviledged API and can only be used by certified applications.
HTML Drag and Drop interfaces enable applications to use drag and drop features in Firefox and other browsers. For example, with these features, the user can select draggable elements with a mouse, drag the elements to a droppable element, and drop those elements by releasing the mouse button.
IndexedDB is a low-level API for client-side storage of significant amounts of structured data, including files/blobs. This API uses indexes to enable high performance searches of this data.
The Page Visibility API lets you know when a webpage is visible or in focus. With tabbed browsing, there is a reasonable chance that any given webpage is in the background and thus not visible to the user.
The High Resolution Time standard defines a Performance interface that supports client-side latency measurements within applications.
The Web Audio API provides a powerful and versatile system for controlling audio on the Web, allowing developers to choose audio sources, add effects to audio, create audio visualizations, apply spatial effects (such as panning) and much more.
The Web Storage API provides mechanisms by which browsers can store key/value pairs, in a much more intuitive fashion than using cookies.
Web Workers are a mechanism by which a script operation can be made to run in a background thread separate from the main execution thread of a web application. The advantage of this is that laborious processing can be performed in a separate thread, allowing the main (usually the UI) thread to run without being blocked/slowed down.