ReactJS interviews can range from simple component and state questions to advanced topics like hooks, context, performance optimization, and architecture. In this guide, we’ve compiled a practical set of questions that are frequently asked in interviews.
The format is interactive: click on a question to reveal the answer, so you can test yourself first or review explanations quickly.
By going through these Q&As, you’ll not only refresh your React knowledge but also learn how to explain your answers confidently, which is key in technical interviews.
What is React?Junior
What are some of the main features of React?Junior
What are components in React?Junior
What is JSX?Junior
What are props?Junior
What is the children prop?Junior
What are some advantages of React?Junior
What are some disadvantages of React?Junior
What are hooks?Junior
Explain the useState hook.Junior
Explain the useEffect hook.Junior
What are the differences between useEffect and useLayoutEffect hooks?Junior
Explain the useContext hook.Junior
Explain the useMemo hook.Junior
Explain the useCallback hook.Junior
Explain the useReducer hook.Junior
Explain the useRef hook.Junior
Give an example of how to use the useRef hook.Junior
How is React different to React Native?Junior
How can you implement routing in a React application?Junior
What is React Router?Junior
How can you make API requests in a React application?Junior
What are some considerations to take into account when making an API request in a React application?Junior
What is an event in React?Mid
How do you create an event in React?Mid
What are synthetic events in React?Mid
What is the difference between onClick and onSubmit in React?Mid
What are some common techniques to handle errors in React components?Mid
How to style components in React?Mid
What are CSS Modules, and how can they help with styling in React applications?Mid
What is unit testing, and how can you apply it to React components?Mid
Name tools that can be used to test React apps?Mid
How to loop inside JSX?Mid
What are React Router hooks, and how can you use them for managing navigation in functional components?Mid
What does lifting state up mean in React?Mid
What does mounted mean in React?Mid
What does unmounted mean in React?Mid
What are lifecycle methods?Mid
Discuss custom hooks in React.Mid
What is NextJS and major features of it?Mid
What is the virtual DOM?Mid
What does reconciliation mean in React?Mid
What are React Fragments?Mid
Can web browsers read JSX directly?Mid
What are the purpose of keys in React lists?Mid
What are the two primary ways of creating components in React?Mid
What are forward refs?Mid
What is a pure function in React?Mid
What is the difference between controlled vs. uncontrolled components in React?Mid
Why can hooks not be conditional in React?Mid
What is an arrow function and how is it used in React?Mid
Explain the key concepts of functional components?Mid
How do you conditionally render components?Mid
Explain the key concepts of class components?Mid
Why use React instead of other frameworks, like Angular?Mid
Explain how component composition can be used to create larger components?Mid
Why is it important to maintain immutability when updating state in React?Mid
What is a React error boundary, and how can it be useful for handling errors in components?Mid
What is a Higher-Order Component (HOC) in React?Mid
What is React.memo, and how can it be used to optimize functional components?Mid
What are the equivalent hooks for common component lifecycle methods in class components?Mid
What is web accessibility (a11y), and why is it important in React applications?Mid
What are ARIA attributes in React, and how can you use them to improve accessibility?Mid
How can you implement lazy loading in a React application, and why is it beneficial?Senior
What is Client-Side Rendering (CSR) in React?Senior
What is Server-Side Rendering (SSR) in React?Senior
What is Static Site Generation (SSG) in React?Senior
What is Incremental Static Regeneration (ISR) in React?Senior
Discuss common strategies to improve the performance of React applications.Senior
What are Progressive Web Apps (PWAs), and how can they enhance the user experience of a React application?Senior
Discuss the importance of caching in React applications and how you might implement it.Senior
Discuss different caching strategies you might use to improve the performance of a React application.Senior
Discuss security best practices you would follow when developing a React application to protect against common vulnerabilities.Senior
What security considerations should you keep in mind when implementing user authentication in a React application?Senior
What is the difference between Element and Component?Senior
Discuss the importance of internationalization (i18n) and localization in a React application, and how would you implement it?Senior
Exlplain hydration in React.Senior
How to facilitate real-time communication in React applications?Senior