angular-http

To fetch data with Angular signals, use the signal-based `httpResource()` and `resource()` patterns. These provide reactive, signal-driven data loading with built-in loading and error states, reducing boilerplate for API interactions.

The best way to handle loading states and API errors is by using signal-based fetching patterns like `resource()`. This approach manages asynchronous data loading reactively, natively exposing loading and error states for your UI components.

You implement HTTP interceptors for authentication by applying custom logic to manipulate requests and responses. The standard Angular `HttpClient` supports interceptors to inject authentication headers and handle errors globally.

Yes, you can still use the traditional `HttpClient` with Angular signals. It is recommended for complex scenarios and Observable-based patterns, allowing you to transition gradually to signal-based data fetching architectures.

You should transition from Observable to signal-based data fetching when you want reactive, signal-driven data loading with built-in state management. Use `httpResource()` for simpler API calls and keep `HttpClient` for complex scenarios.