Implementing reducers

In the first chapter, we learned about reducers, functions that take the current state and an action and return the new state of the application. As you now know, actions only describe what happened. Reducers use that information to compute the new state.

To be able to figure out state changes, we should first think about the state of our application. We have already done this in the first chapter, and our state looks as follows:

{ 
  posts: [ 
    { user: 'dan', category: 'hello', text: 'Hello World!' }, 
    { user: 'des', category: 'welcome', text: 'Welcome to the blog' } 
  ], 
  filter: 'hello' 
}

As you can see, we have two separate sub-states in the main state object: posts and filter. This is a good hint for making two reducers: a postsReducer to handle the posts sub-state, and a filterReducer to handle the filter sub-state.

Note

Try to structure your application state in such a way that each feature has its own sub-state of data to work on.

If we wanted to add more...