20 Advanced React Interview Questions API to Clear Senior Engineering Loops

Senior engineering interview processes emphasize layout stability, browser rendering updates, and concurrent hook architectures. Let's look at advanced React evaluation points.

Q1: Explain React concurrent rendering and interruptible renders.

In traditional rendering loops, once React starts drawing updates, it blocks high-priority browser input clicks until finished. Concurrent features solve this by chunking component execution.

Q2: What is the React Fiber architecture?

Fiber is React's reconciliation algorithm that enables incremental rendering. It allows React to pause, abort, or resume work based on priority levels.

Q3: How does useMemo differ from React.memo?

useMemo memoizes a computed value within a component, while React.memo prevents re-renders entirely when props haven't changed.

Q4: When should you use useReducer over useState?

Use useReducer when state logic is complex, involves multiple sub-values, or when the next state depends on the previous one.

Q5: Explain the difference between controlled and uncontrolled components.

Controlled components have their value managed by React state, while uncontrolled components manage their own state via the DOM.