Observables and rxjs

Observables

It is a concept introduced by RxJS library to handle asynchronous data streams

Signals vs Observables

• Observables are values over time, while signals are values in a container that don’t need a subscription to be accessed
• With signals, rxjs is not required anymore for reactivity, but since signals are a new concept from version 17 of Angular, you may see a lot of legacy code using observables
• Rxjs Observables can be less verbose than signals when dealing with complex data transformations and operators, for example when using operators like map, filter, switchMap, debounceTime, etc.
• Observables are great for managing events and streamed data whereas signals are better suited for managing application state
• Signals can be converted to observables using toObservable() and observables can be converted to signals using toSignal()
• Observables have no initial value, whereas signals always have an initial value

Angular HttpClient Observables

HttpClient observables are short-lived by design. They emit a single value and then complete, which automatically triggers a cleanup process, preventing memory leaks.