What Is AngularJS?

AngularJS is a JavaScript framework mostly used to build single-page applications (SPAs). It was developed by Google and is open source. First announced in 2010, it drew attention by offering a more effective and modular approach to building web applications.

AngularJS is built around the MVC (Model-View-Controller) design pattern. The pattern splits an application into three parts — the data (Model), the user interface (View) and the application logic (Controller) — and manages how they interact.

The main features of AngularJS are:

1. Two-Way Data Binding: Changes in the model are reflected in the user interface automatically, and changes in the user interface are passed back to the model.
2. Modularity: AngularJS is good at splitting an application into small, independent and reusable modules, which makes development easier to manage.
3. Dependency Injection: AngularJS has an injection system for managing dependencies, which makes sharing data and services between components easier.
4. Directives: Directives added to HTML elements let you extend HTML with your own syntax and attach dynamic behaviour to the page.
5. Templating: HTML templates bound to the model make it easy to build dynamic user interfaces.
6. Routing: A routing system lets users move between different views inside the application.

AngularJS became popular because it helped developers build and manage complex applications more effectively. However, it has been replaced by Angular (version 2 and later), which is generally recommended for new projects.

Note: Official long-term support (LTS) for AngularJS ended on 31 December 2021; it no longer receives security updates. New projects should use Angular or another maintained framework.