Explain the dispatch function returned by the useReducer hook.

0-2 years experience

1. 1If you have a component using useReducer to manage a counter, how would you trigger an increment using the dispatch function?
2. 2What does React do when you call dispatch with an action that isn’t handled in your reducer’s switch statement?
3. 3How would you include additional data, like a payload, when dispatching an action?

2-5 years experience

1. 1You added a new action type to your reducer but the UI isn’t updating. Walk me through how you’d debug the dispatch flow.
2. 2Why might dispatching several actions sequentially inside one click handler not produce the state you expect?
3. 3If you need to fetch data before updating state, how would you structure the async call and subsequent dispatches?

5-8 years experience

1. 1In a large form with many fields, you consider switching from many useState calls to a single useReducer. What trade‑offs does the dispatch function introduce for performance and code clarity?
2. 2How would you create a reusable reducer and a typed dispatch wrapper that can be shared across multiple components?
3. 3When you combine useReducer with React Context for global state, what pitfalls can arise with the dispatch function and how would you avoid them?

8+ years experience

1. 1Your team is migrating a legacy class component that uses setState to a functional component using useReducer for complex state. What architectural considerations guide how you expose the dispatch function to other modules?
2. 2If several micro‑frontends need to coordinate state updates, would you rely on a shared dispatch from useReducer or choose another pattern? Explain your reasoning.
3. 3How would you version and evolve the shape of actions and reducer logic in a long‑lived codebase without breaking existing dispatch calls?