AngularJS, commonly referred to as Angular, is an open-source web application framework maintained by Google and a community of individual developers and corporations to address many of the challenges encountered in developing single-page applications. Its goal is to simplify both development and testing of such applications by providing a framework for client-side model–view–controller (MVC) architecture, along with components commonly used in rich internet applications.

The library works by first reading the HTML page, which has embedded into it additional custom tag attributes. Those attributes are interpreted as directives telling Angular to bind input or output parts of the page to a model that is represented by standard JavaScript variables. The values of those JavaScript variables can be manually set within the code, or retrieved from static or dynamic JSON resources.

Philosophy

AngularJS is built around the belief that declarative programming should be used for building user interfaces and connecting software components, while imperative programming is better suited to defining an application's business logic. The framework adapts and extends traditional HTML to present dynamic content through two-way data-binding that allows for the automatic synchronization of models and views. As a result, AngularJS de-emphasizes DOM manipulation with the goal of improving testability and performance.

AngularJS's design goals include:

• Decouple DOM manipulation from application logic. This difficulty is dramatically affected by the way the code is structured.
• Decouple the client side of an application from the server side. This allows development work to progress in parallel, and allows for reuse of both sides.
• Provide structure for the journey of building an application: from designing the UI, through writing the business logic, to testing.