If you are preparing for a React UI Developer interview, this comprehensive list of questions covering React, Redux, Storybook, HTML, CSS, Accessibility (A11Y), and Unit Testing will help you ace it.
1. React Interview Questions
Core Concepts
- What are the key features of React?
- Explain the virtual DOM and why it improves performance.
- What is the difference between controlled and uncontrolled components?
- How does React handle re-renders, and how can we optimize performance?
- What are React Fragments, and why would you use them?
Hooks & Functional Components
- What are React hooks, and how do they differ from class lifecycle methods?
- Explain the useEffect dependencies and common pitfalls while using it.
- What is useCallback and useMemo, and when should you use them?
- How does useRef differ from document.getElementById()?
- How does context API work, and when should you use it instead of Redux?
Component Design & State Management
- How would you design a reusable component in React?
- What is prop drilling, and how does the context API solve it?
- How do you handle error boundaries in React?
- Explain HOC (Higher-Order Components) and how they compare to hooks.
- What is lazy loading, and how does it improve performance?
2. Redux Interview Questions
State Management Concepts
- What are the core principles of Redux?
- Explain actions, reducers, and stores in Redux.
- What is the difference between connect() and hooks like useSelector & useDispatch?
- What is Redux Thunk vs. Redux Saga? When would you use them?
- How would you structure a Redux store for a large-scale application?
3. Storybook Interview Questions
- What is Storybook, and how does it help in frontend development?
- How do you set up a component in Storybook?
- How can you test interactions using Storybook Addons?
- What are controls and args in Storybook, and how do they help with component testing?
- How do you handle accessibility testing in Storybook?
4. HTML & CSS Interview Questions
HTML Concepts
- What are semantic HTML elements, and why are they important?
- How do you optimize HTML for SEO?
- What are different types of ARIA roles, and how do they help in accessibility?
- How does the defer and async attribute affect script loading?
- What are custom elements in HTML?
CSS Concepts
- What is the difference between relative, absolute, and fixed positioning?
- Explain the CSS Box Model and how margin/padding affect layout.
- How does CSS specificity work, and how do you resolve specificity conflicts?
- What are CSS Flexbox and CSS Grid? When would you use one over the other?
- How do you optimize CSS for performance?
5. Accessibility (A11Y) Interview Questions
- What is WCAG, and what are its different levels (A, AA, AAA)?
- What are ARIA attributes, and when should you use them?
- How do you make a modal dialog accessible?
- How would you make a tooltip accessible to screen readers?
- How do you test accessibility in a React application?
6. Unit Testing Interview Questions
React Testing Library & Jest
- What are the differences between unit tests, integration tests, and end-to-end tests?
- How do you test a React component that fetches data from an API?
- How do you mock an API request in Jest?
- What is act() in React Testing Library, and why is it needed?
- What’s the difference between toBe(true) and toBeTruthy() in Jest?
7. Advanced & Performance Optimization
- How do you handle code splitting and lazy loading in React?
- What are best practices for writing scalable React applications?
- How do you prevent unnecessary re-renders in React?
- How does server-side rendering (SSR) work in React?
- How do you measure and improve First Contentful Paint (FCP) and Time to Interactive (TTI) in a React app?
Preparing for a frontend interview requires a solid grasp of React, Redux, Storybook, HTML, CSS, Accessibility (A11Y), and Unit Testing. The above questions cover fundamental and advanced topics to help you get ready for your next React UI Developer interview.
If you found these questions helpful or have additional insights to share, feel free to drop your feedback in the comments! Also, let us know if there are specific areas you’d like us to cover in more detail in future blog posts.
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