Generally, as granular as possible. This allows for easier organizion, debugging, and testing. It also allows you to more easily add new features or remove features in the future. src
PRO! Having multiple reducers fire on a shared action is a great way to handle complex state changes in a predicable, reliable, and modular way, as long as it is intended.
Use explicit names for each action to prevent unintended firing (i.e. don’t use ‘RESET’ for every reducer… unless you want them all to reset at the same time!)
store - the object created by redux that stores all states for a given application. This is the single source of truth for our application.
combined reducers - a way redux allows us to ‘export’ many reducer files from a single source to our store, so that they are all available in different parts of an app.