Check out a free preview of the full Reactive Angular 2 with ngrx course:
The "Reducers" Lesson is part of the full, Reactive Angular 2 with ngrx course featured in this preview video. Here's what you'd learn in this lesson:
A reducer is a method that takes in the current state and an action. Based on the action, the reducer will return a new state. Reducers and their initial state are registered in the application with provideStore. After talking about reducers, Lukas demonstrates how the store.select() and store.dispatch() methods are used.