data fetching), but also for a centralized control flow of state transitions in your applications. They are not only used for asynchronous logic (e.g. Popular side-effect libraries in Redux are Redux Thunk and Redux Saga. If you are using useReducer + useContext as replacement for Redux, you may miss this rich ecosystem of middleware for your React application. Since it's not one global state container (see previous section), it's difficult to apply such middleware globally, but also it's not easily done to convert Redux's middleware 1:1 for useReducer in the first place. There is no middleware for useReducer (yet). That's only one example for a middleware in Redux though. You can see how your state looks like after and before the dispatched action went through your reducers. A simple example for a middleware in Redux is the action logger: Every action that goes through Redux will be logged in your browser's developer tools. ![]() Redux comes with a rich middleware ecosystem. You can think of Redux as one global event bus which takes any events (actions) and processes them into a new state based on the action's payload and the previous state. Whereas in Redux, the dispatch function sends the action object to the store which distributes it to all its combined reducer functions. We dispatch action objects to that reducer only. The useReducer function is tightly coupled to its reducer which holds also true for its dispatch function. While useReducer with its reducer is a part of how Redux works, it isn't Redux. The dispatch function from useReducer, in contrast, only deals with actions that are specified by the reducer function to be consumed. Redux provides one dispatch function that consumes any action dedicated for any reducer function. There is no native feature (yet) which combines all dispatch functions to one dispatch function. Global: Second, every useReducer comes with its own dispatch function. Only if we were able to combine all state containers from all useReducer hooks, we could speak of one state container. Redux is offering this feature, but in plain React we would have to implement it ourselves. One: First, there is no native feature (yet) which combines all reducers to one ultimate reducer. There are two ingredients missing to make it one and global as in Redux. However, even though we are able to lift all the useReducer state up to our most top-level component - almost making Redux obsolete because it can be seen as global state container - it still isn't one global state container. ![]() Let this fact sink for a moment before we continue extending useReducer's component co-located state management philosophy. ![]() While Redux creates one global state container - which hangs somewhere above your whole application -, useReducer creates a independent component co-located state container within your component. Where your state is managed is a crucial difference between Redux and useReducer. Global State Container and Component Co-Located State Also if you want to learn more about Redux, check out this extensive Redux tutorial. It's good to know about the fundamentals before entering this discussion about Redux vs useReducer. Requirements: Check out the following tutorials, if you haven't learned about reducers in JavaScript or useReducer in React. Now, many people keep wondering: Does useContext and useReducer replace Redux? As of the time of writing this article, React Hooks don't replace Redux. There are two hooks that are used for modern state management in React (useState and useReducer) and one hook called useContext to use React's Context API to pass state or state updater functions down the component tree. Since React Hooks have been released, function components can use state and side-effects.
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