What does an HttpInterceptor do in Angular?

An HttpInterceptor in Angular plays a significant role in managing HTTP requests and responses globally. It acts as a middleware that can be used to intercept and change both the outgoing requests from the application to the server and the incoming responses back to the application. This capability allows developers to centralize certain functionalities, such as adding common headers, logging, handling errors, and modifying requests or responses in a consistent manner across the entire application.

By implementing an HttpInterceptor, you can ensure that all HTTP calls are processed in one place rather than scattering similar logic throughout different parts of the application. This greatly enhances code maintainability and readability. For example, you could use an interceptor to automatically attach an authorization token to all outgoing requests without needing to manually include it in each service call.

The other options touch on important concepts but do not accurately reflect the primary responsibility of an HttpInterceptor. For instance, while handling user authentication is a common use case for interceptors, it is not their sole purpose. Similarly, interceptors do not serve static files or modify the URL directly for API calls—they may modify request parameters or headers, but they do not focus on the file serving or URL manipulation as their main function. Thus, the answer emphasizes the comprehensive role of interceptors in the