We can create a slice by manually defining reducers, actions, and the action objects for a feature, however, that is not the convention as it's a tedious process, and there is a better alternative.

The createSlice function creates and returns a new slice object which contains the actions, action creator(s), and slice reducer(s):

The above is an example of a simple Todo feature slice. The createSlice function automatically generates the action creators for us, which can then be used for dispatches from the React components.

Recall that an action is an object with a type key and an optional payload key. An action creator is a function that generates and returns an action object, we use these to ease the process.

We can manually create action objects like this:

However, createSlice creates action creators for us based on the actions we passed in the createSlice argument object. For example in the above case, the addTodo generated by createSlice may look like this:

The first part, 'todo', is from the name of the slice, while the second part, addTodo, is the name of the action's key. Hence it is todo/addTodo.

To sum up, the following is the complete code of todosSlice.js:

Since the generated action creators and the slice reducers will be needed in index.js and other React component files, we need to export them, in the end, to make them usable.