UseState Interview Questions

Use a controlled radio group with useState to capture the selected value and reflect it in another element.

Use controlled inputs with useState to mirror user-typed text into another element in real time.

Toggle element visibility in React by combining useState with conditional rendering or CSS. Know when to unmount vs keep mounted.

Build the same counter component with both useState and useReducer. Understand the tradeoffs and know when to reach for each.

Build chained dropdowns where the second options list derives from the first selection. Extend the pattern to API-driven options and three-level chains.

Track a select value in state and display it anywhere on the page. This is the controlled component pattern applied to dropdowns and is the foundation for summary panels and confirmation UIs.

React forms work through controlled inputs where state is the single source of truth. Understand the cycle, real-time validation, input formatting, and the multi-field pattern with a shared handler.

Correctly add items to an array in React state using spread, concat, or functional updates without mutating the original array.

Understand what hooks are, the rules that govern them, and how useState and useEffect replace class component state and lifecycle methods.