Explain the concept of actions in Redux.

0-2 years experience

1. 1How would you create and dispatch an action to add a new item to a todo list in a Redux store?
2. 2If you dispatch an action with a typo in its type field, what will happen in the reducer?
3. 3What does the payload property represent in a Redux action, and how would you use it when updating state?

2-5 years experience

1. 1We have a feature where users can edit a profile, but after dispatching the UPDATE_PROFILE action, the UI doesn't reflect the changes. Walk me through how you'd debug this.
2. 2When designing action types for a large app, would you prefer string constants or a utility like createAction from Redux Toolkit? Explain the trade‑offs.
3. 3Suppose you need to batch multiple related actions into a single network request. How would you structure the actions and what middleware might you use?

5-8 years experience

1. 1Our application experiences performance issues because every action causes the entire state tree to be re‑serialized for logging. How would you redesign the action handling or logging to mitigate this at scale?
2. 2We are migrating from plain action objects to using Redux Toolkit's createAction and createSlice. What architectural considerations and potential pitfalls should we watch for during the migration?
3. 3In a micro‑frontend setup, different teams dispatch actions that may collide in type names. How would you design a naming convention or system to avoid conflicts while keeping actions discoverable?

8+ years experience

1. 1Our organization has multiple legacy Redux codebases, each with its own action naming scheme. We want to unify them under a single convention without breaking existing apps. Outline a migration strategy and governance model.
2. 2When introducing a new cross‑cutting feature like feature flags that needs to affect many reducers, how would you design the action payload and handling to minimize coupling and support future extensions?
3. 3Considering long‑term maintainability, how would you evaluate whether to keep using Redux actions at all versus moving to an event‑sourcing or CQRS approach for a high‑throughput system?