In this chapter, we have successfully created a flashcard app where you can add/edit/delete flashcards and also create a service to manage the business logic related to flashcards. In the end, we used observables in our services, which makes it easier to manage the state of an application. We also used immutability to improve performance by using the OnPush change detection strategy.

In the next chapter, we will create a single-page application (SPA) personal blog using the WordPress API and make some performance improvements to the application.