Browser APIs
The features provided by the browser.
Fetch
This kind of functionality was previously achieved using XMLHttpRequest. Fetch provides a better alternative that can be easily used by other technologies such as Service Workers. Fetch also provides a single logical place to define other HTTP-related concepts such as CORS and extensions to HTTP. MDN
i18n
The Intl object is the namespace for the ECMAScript Internationalization API, which provides language sensitive string comparison, number formatting, and date and time formatting. The Intl object provides access to several constructors as well as functionality common to the internationalization constructors and other language sensitive functions. MDN
Local Storage
The read-only localStorage property allows you to access a Storage object for the Document's origin; the stored data is saved across browser sessions. MDN
Service Workers
Service workers essentially act as proxy servers that sit between web applications, the browser, and the network (when available). They are intended, among other things, to enable the creation of effective offline experiences, intercept network requests and take appropriate action based on whether the network is available, and update assets residing on the server. They will also allow access to push notifications and background sync APIs. MDN
Web Animations
The Web Animations API lets us construct animations and control their playback with JavaScript. This article will start you off in the right direction with fun demos and tutorials featuring Alice in Wonderland. MDN
Web Audio
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. MDN
Web Components
As developers, we all know that reusing code as much as possible is a good idea. This has traditionally not been so easy for custom markup structures — think of the complex HTML (and associated style and script) you've sometimes had to write to render custom UI controls, and how using them multiple times can turn your page into a mess if you are not careful. MDN
WebGL
WebGL enables web content to use an API based on OpenGL ES 2.0 to perform 2D and 3D rendering in an HTML canvas in browsers that support it without the use of plug-ins. MDN
WebRTC
WebRTC (Web Real-Time Communication) is a technology which enables Web applications and sites to capture and optionally stream audio and/or video media, as well as to exchange arbitrary data between browsers without requiring an intermediary. MDN
WebSocket
The WebSocket API is an advanced technology that makes it possible to open a two-way interactive communication session between the user's browser and a server. With this API, you can send messages to a server and receive event-driven responses without having to poll the server for a reply. MDN
Web Speech API
The Web Speech API makes web apps able to handle voice data. There are two components to this API: MDN
WebVR
WebVR provides support for exposing virtual reality devices — for example, head-mounted displays like the Oculus Rift or HTC Vive — to web apps, enabling developers to translate position and movement information from the display into movement around a 3D scene. This has numerous, interesting applications, from virtual product tours and interactive training apps to immersive first-person games. MDN