Important APIs

DOM-API

Document Object Model Application Programming Interface for manipulating H.T.M.L. Documents.

CANVAS-API

Drawing of Graphics and Rendering Animations..

WEB STORAGE-API

For the storage of data locally {localStorage, sessionStorage}.

GEOLOCATION-API

For accessing of Device location(s).

DRAG AND DROP-API

For handling drag-&-drop interactions.

FILE-API

For working with files {fileReader, fileWriter, fileList}.

HISTORY-API

For manipulating browser's history.

FULLSCREEN-API

For the toggling of full-screen mode.

NOTIFICATIONS-API

For displaying notifications.

WEB WORKERS-API

For running scripts in background threads.

CONSOLE-API

For logging and debugging.

DATE-API

For working with Dates and Times.

MATH-API

For mathematical functions {Math.random etc.}.

REGULAR EXPRESSION-API

For working with Regular Expresions.

STRING-API

For string manipulation processes {e.g., trim, split}.

ARRAY-API

For working with arrays {e.g., push, pop, map}..

OBJECT-API

For working with Objects {e.g., keys, values}.

PROMISE-API

For handling asynchronous operations.

FETCH-API

For making HTTP-requests

WEB SOCKET-API

For real time communications.

WINDOW-API

For interacting with the browsers' window.

NAVIGATOR-API

For accessing browsers' information {e.g., userAgent}.

SCREEN-API

For accessing screen's information {e.g., width, height}.

LOCATION-API

For accessing and manipulating the URL.

There are thousands of JavaScript libraries available, each serving different purposes such as DOM manipulation, data visualization, testing, and more. Some of the most popular and widely used libraries include: 

• DOM Manipulation: jQuery, a fast, small, and feature-rich library used for simplifying HTML DOM tree traversal and manipulation, event handling, and Ajax.
• User Interface (UI) Development:
  • React: A popular library developed by Facebook for building user interfaces using a component-based approach and a virtual DOM.
  • jQuery UI: An extension for jQuery focused on creating graphical user interfaces with interactive elements and widgets.
• Data Visualization: D3.js (Data-Driven Documents), a powerful library for manipulating documents based on data and creating dynamic, interactive data visualizations using HTML, SVG, and CSS.
• Utility Functions:
  • Lodash: Provides utility functions for common programming tasks, making it easier to work with arrays, strings, objects, and numbers.
  • Underscore.js: A lightweight utility belt library that provides helper functions for everyday tasks.
• Animation and Graphics:
  • Three.js: A library for creating and displaying animated 3D computer graphics in a web browser using WebGL.
  • Anime.js: A lightweight animation library with a simple, powerful API for animating CSS, individual transforms, SVG, and JavaScript objects.
• Testing:
  • Jest: A delightful JavaScript testing framework focused on simplicity and supporting large-scale web applications.
  • Mocha: A feature-rich test framework for JavaScript running on Node.js and the browser, making asynchronous testing simple.
  • Jasmine: A behavior-driven development (BDD) testing framework that does not rely on a DOM or a specific browser. 

Other notable categories include:

• Back-end development (runtime environments and frameworks): Node.js (runtime, not a library), Express.js (framework for Node.js), Meteor.js (full-stack framework).
• Mobile app development: Ionic (framework), React Native (framework).
• Machine Learning: TensorFlow.js, Brain.js.