List some good practices while using state

0-2 years experience

1. 1How would you initialize a piece of state that depends on a prop value, and why would you choose that approach?
2. 2If you notice a component re‑rendering twice after a button click that updates state, what could be causing it and how would you fix it?
3. 3When you need to update an object in state, how would you do it to avoid mutating the original state?

2-5 years experience

1. 1You’re adding a form with multiple input fields that share validation state. How would you structure the state, and what trade‑offs does your approach have?
2. 2During a sprint you discover that a component’s state is causing a memory leak when a subscription isn’t cleaned up. Walk me through how you’d debug and resolve it.
3. 3Explain why lifting state up to a parent caused a performance regression in a list component, and how you’d address it.

5-8 years experience

1. 1Our dashboard renders thousands of rows with per‑row expand/collapse state. How would you design the state management to keep the UI responsive?
2. 2We’re migrating from local component state to a global store. What criteria would you use to decide which pieces of state to move, and how would you ensure consistency?
3. 3Describe how you’d prevent unnecessary re‑renders when multiple components read the same slice of state, considering memoization and selector patterns.

8+ years experience

1. 1Across several teams we have duplicated state handling logic for feature toggles. How would you create a shared, scalable solution while minimizing coupling?
2. 2Our legacy codebase mixes class component state, Redux, and React Context. Outline a migration plan to unify state management, addressing backward compatibility and developer onboarding.
3. 3When designing a library of reusable UI components, what conventions would you enforce for internal state vs. controlled props to ensure composability and testability?