+100 Next.js Interview Questions (With Answers)

100 Essential Next.js Interview Questions to Level Up Your Web Development Skills.

1. What is Next.js?

Next.js is a popular React framework designed for building scalable, production-ready web applications. It provides features like server-side rendering, static site generation, and API routes.

2. What are the key features of Next.js?

Key features of Next.js include:

• Server-Side Rendering (SSR)
• Static Site Generation (SSG)
• Incremental Static Regeneration (ISR)
• API Routes
• File-based routing
• Image Optimization
• Automatic code splitting

3. How is Next.js different from React.js?

While React.js is a library for building UIs, Next.js is a framework built on top of React, providing additional features such as SSR, SSG, and routing out of the box.

4. What are the advantages of using Next.js over React.js?

Next.js offers:

• Better SEO performance through SSR.
• Built-in routing with file-based routing.
• Static site generation for faster page loads.
• Automatic code-splitting, leading to better performance.

5. How does Server-Side Rendering (SSR) work in Next.js?

SSR in Next.js allows pages to be rendered on the server at request time, ensuring that the page’s content is available to search engines and improving the initial load time.

6. What is Static Site Generation (SSG) in Next.js, and when would you use it?

SSG generates HTML at build time for fast loading and improved SEO. It’s ideal for pages that don’t change often, such as blogs or marketing pages.

7. What are API routes in Next.js, and how do they work?

API routes allow you to build backend functionality directly in your Next.js app. These are serverless functions that handle HTTP requests like GET, POST, PUT, etc.

8. What is Incremental Static Regeneration (ISR) in Next.js, and how is it different from SSG?

ISR enables static content to be updated after the site has been built, allowing you to regenerate pages in the background while serving static content to users.

9. How do you handle dynamic routes in Next.js?

Dynamic routes in Next.js are handled using brackets ([]). For example, pages/[id].js will create dynamic routes based on the id parameter.

10. How does code splitting work in Next.js?

Next.js automatically splits code by page. This means only the necessary code for each page is loaded, improving performance and reducing bundle size.

11. What is the difference between Static Rendering (SSG) and Server Rendering (SSR) in Next.js?

• SSG generates HTML at build time and serves it for faster page loads.
• SSR generates HTML on the server for each request, ensuring dynamic content.

12. What is the App Router in Next.js?

The App Router in Next.js is a new routing system introduced to simplify the routing mechanism, offering enhanced flexibility and control compared to the Pages Router.

13. How do layouts work with the App Router?

Layouts in the App Router allow you to structure reusable components across multiple pages, making it easier to manage UI consistency and shared components.

14. What is the difference between the app directory and the pages directory?

The app directory is used with the new App Router and supports features like layouts, loading states, and more advanced routing capabilities. The pages directory is used in the traditional Pages Router.

15. What are Server Components and Client Components in Next.js?

• Server Components are rendered on the server and sent as HTML.
• Client Components are rendered on the client and allow for interactivity.

16. How does Next.js improve SEO compared to traditional client-side rendering?

Next.js supports SSR and SSG, which generates pre-rendered HTML content, making it more SEO-friendly compared to traditional client-side rendering (CSR).

17. How does Next.js handle environment variables?

Environment variables are handled via .env files (e.g., .env.local) and can be accessed in both the client and server-side code using process.env.

18. How do you create dynamic API routes in Next.js?

Dynamic API routes are created by using the same bracket notation ([param]) in the pages/api directory.

19. What is Middleware in Next.js, and how do they work?

Middleware allows you to run code before a request is completed, enabling features like authentication, logging, or redirecting users.

20. What are React Server Components, and how are they used in Next.js?

React Server Components allow parts of the UI to be rendered on the server, reducing the client-side JavaScript bundle size.

21. How React Server Components Work:

React Server Components allow rendering on the server, improving performance by sending only necessary JavaScript to the client.

22. How to Use React Server Components in Next.js:

To use React Server Components in Next.js, create a .server.js file in the appropriate directory, allowing the component to be rendered server-side.

23. Benefits of Using React Server Components:

• Reduced client-side JS.
• Better performance.
• Improved scalability.

24. What is next/link, and how does it differ from a standard tag?

next/link is a React component for client-side navigation, providing prefetching and reducing page reloads, unlike a standard tag.

25. What is next/image, and what are its advantages?

next/image automatically optimizes images for better performance, including resizing, lazy loading, and WebP support.

26. What are rewrites in Next.js, and how do they work?

Rewrites allow you to map an incoming request path to a different destination without changing the URL in the browser.

27. What is the next.config.js file, and what is its role?

next.config.js is a configuration file in Next.js that allows you to customize the build process, routing, environment variables, and more.

28. How does Next.js handle image optimization?

Next.js optimizes images by automatically resizing, compressing, and serving them in the most appropriate format for the client.

29. What is Next.js’s hybrid rendering?

Hybrid rendering in Next.js allows you to use SSR, SSG, or ISR on a per-page basis, providing flexibility in how content is rendered.

30. What are the main benefits of hybrid rendering in Next.js?

Hybrid rendering offers the ability to combine different rendering strategies to maximize performance, SEO, and flexibility.

31. Explain how data fetching works in Next.js.

Data fetching in Next.js can be done using getStaticProps (SSG), getServerSideProps (SSR), or getInitialProps.

32. How do you manage state in a Next.js application?

State management in Next.js can be done using React’s useState and useContext, or with libraries like Redux, Recoil, or Zustand.

33. How does routing work in Next.js?

Routing in Next.js is based on the file system. The files in the pages directory automatically become routes.

34. How can you handle nested routing in Next.js?

Nested routing is handled by creating subdirectories inside the pages directory. For example, pages/blog/[id].js supports dynamic routes.

35. What is the purpose of the public folder in a Next.js project?

The public folder is used for static assets like images, fonts, or other files that can be accessed directly via URL.

36. How do you create a custom 500 error page in Next.js?

To create a custom 500 error page, create a pages/_error.js file and customize the error handling for both 404 and 500 errors.

37. How does file-based routing work in Next.js?

File-based routing automatically maps files in the pages directory to routes based on their file names and structure.

38. What are the options for styling components in Next.js?

You can style components using traditional CSS, CSS-in-JS libraries like styled-components, or CSS modules.

39. How does TypeScript work with Next.js?

Next.js has built-in support for TypeScript. You can create a tsconfig.json file, and it will automatically detect and work with TypeScript files.

40. How can you configure TypeScript in Next.js?

Simply add a tsconfig.json file to your project root. Next.js will automatically configure TypeScript for you, and you can start using .ts and .tsx files.

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