NgRx
interview questions.

Answer based on actual experience. If you have used NgRx, explain actions, reducers, selectors, effects, and how you test each. Reducers should be tested as pure functions; effects can be tested with mocked action/service streams; components can be tested with a mock store. Do not claim NgRx production experience if you have not used it.

A reducer is a pure function that calculates the next state from the previous state and a dispatched action. It must not mutate existing state or perform API calls; side effects belong in effects or other appropriate services.

We can use services, and they are often the simpler choice. NgRx helps when complex shared state benefits from predictable action-driven updates, selectors, effects, devtools and testability. Services with RxJS or signals work well for local or moderately shared state. Choose based on complexity, not because NgRx is mandatory.