React Interview Questions Your Guide to Success
React is a popular JavaScript library for building user interfaces. Jobpe provides comprehensive React interview questions to help you master component architecture, hooks, state management, and more.
react
- Frontend
What is the virtual DOM in React and why is it important?
The virtual DOM is a lightweight copy of the real DOM used by React to optimize updates and improve performance.
Explain how React hooks like useState and useEffect work.
useState manages state in functional components; useEffect runs side effects like data fetching or subscriptions.
What is JSX and how does it differ from HTML?
JSX is a syntax extension allowing HTML-like code in JavaScript, which React compiles to create UI elements.
Describe the component lifecycle in React class components.
Lifecycle methods like componentDidMount and componentWillUnmount let you run code at specific phases of a component's life.
How do you optimize performance in React applications?
Techniques include memoization, code splitting, lazy loading, and avoiding unnecessary renders.
What are higher-order components (HOCs)?
HOCs are functions that take a component and return an enhanced component with additional props or behavior.
Explain the difference between controlled and uncontrolled components.
Controlled components have state managed by React; uncontrolled components rely on the DOM to manage state.
What is the Context API and when would you use it?
Context API provides a way to pass data through the component tree without prop drilling, useful for global state.
How do error boundaries work in React?
Error boundaries catch JavaScript errors in components and display fallback UI instead of crashing the whole app.
Describe the difference between React and React Native.
React is for web apps using the DOM, React Native builds mobile apps using native components.
Frontend
What is the virtual DOM in React and why is it important?
The virtual DOM is a lightweight copy of the real DOM used by React to optimize updates and improve performance.
Explain how React hooks like useState and useEffect work.
useState manages state in functional components; useEffect runs side effects like data fetching or subscriptions.
What is JSX and how does it differ from HTML?
JSX is a syntax extension allowing HTML-like code in JavaScript, which React compiles to create UI elements.
Describe the component lifecycle in React class components.
Lifecycle methods like componentDidMount and componentWillUnmount let you run code at specific phases of a component's life.
How do you optimize performance in React applications?
Techniques include memoization, code splitting, lazy loading, and avoiding unnecessary renders.
What are higher-order components (HOCs)?
HOCs are functions that take a component and return an enhanced component with additional props or behavior.
Explain the difference between controlled and uncontrolled components.
Controlled components have state managed by React; uncontrolled components rely on the DOM to manage state.
What is the Context API and when would you use it?
Context API provides a way to pass data through the component tree without prop drilling, useful for global state.
How do error boundaries work in React?
Error boundaries catch JavaScript errors in components and display fallback UI instead of crashing the whole app.
Describe the difference between React and React Native.
React is for web apps using the DOM, React Native builds mobile apps using native components.
