8 Advanced React Interview Questions you should absolutely know

Q1. What is React context, and how is it used?

React context provides a way to pass data through the component tree without explicitly passing props at every level. It enables the sharing of state between components.

Q2. What are React hooks? Explain some commonly used hooks.

React hooks are functions introduced in React 16.8 that allow you to use state and other React features in functional components. Some commonly used hooks include useState, useEffect, useContext, and useRef.

Q3. Explain the concept of Virtual DOM in React.

The Virtual DOM is a lightweight copy of the actual DOM that React uses for efficient rendering. React compares the Virtual DOM with the previous version to determine the minimal number of updates needed and applies those updates to the actual DOM.

Q4. What is the significance of the key prop in React?

The key prop is used to uniquely identify elements in a list. It helps React efficiently update and re-render only the necessary components when the list changes, improving performance.

Q5. How does React handle event propagation?

React uses a synthetic event system to handle event propagation. When an event occurs, React captures it at the root of the component tree and delegates it to the appropriate event handlers, allowing for efficient event handling.

Q6. What is the purpose of React Fragments?

React Fragments allow you to group multiple elements together without adding an extra node to the DOM. They are useful when you need to return multiple elements from a component without a wrapper div or other container.

Q7. What is the significance of the shouldComponentUpdate lifecycle method?

The shouldComponentUpdate method allows you to optimize the rendering performance of a component. By implementing this method, you can control whether the component should re-render based on changes in its props or state.

Q8. How can you optimize the performance of a React application?

Performance optimization techniques in React include minimizing unnecessary re-renders using shouldComponentUpdate or React.memo, using React's memoization techniques like useMemo and useCallback, lazy loading components using React.lazy, and code splitting using dynamic imports.

These advanced React interview questions cover important concepts and can help you demonstrate your in-depth knowledge of React during interviews.