49 Essential Next.js Interview Questions to Assess Your Candidates

Looking to strengthen your development team with a Next.js expert? Identifying candidates who possess the right skills and knowledge in this powerful React framework is crucial for building high-performance applications.

To aid in your selection process, we’ve compiled a comprehensive list of 49 essential Next.js interview questions. These questions are designed to dive deep into the candidates' understanding of the framework, its features, and best practices.

Additionally, we’ve provided answers to the 27 most critical questions, allowing you to gauge candidates' responses meaningfully, even if you’re not a Next.js specialist yourself.

So, how do you streamline your interviewing process?

With our Next.js Fundamentals test, the answer is straightforward. Ask candidates to complete this assessment alongside other relevant tests from our extensive library. This will help you pinpoint the top talents quickly. After that, invite the best candidates for an interview and use the following questions to evaluate their expertise in Next.js.

Top 27 Next.js Interview Questions to Hire Skilled Professionals

Below, you’ll find 27 interview questions and answers that will help you assess applicants’ Next.js skills and knowledge. You can use them for various roles involving Next.js, from junior developers to full-stack engineers.

1. What is Next.js?

Next.js is a React framework that enables functionality such as server-side rendering and static website generation for React-based applications. It aims to create a better developer experience with features like file-based routing and API routes.

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

The main features of Next.js include:

• Server-Side Rendering (SSR)
• Static Site Generation (SSG)
• File-Based Routing
• API Routes
• Automatic Code Splitting
• Image Optimization

3. How does Next.js handle routing?

Next.js uses a file-based routing system where each file in the pages directory automatically becomes a route. For example, pages/about.js will be accessible at /about.

4. What is the difference between Static Generation and Server-Side Rendering?

• Static Generation: The HTML is generated at build time and served as static files. This results in faster load times but does not update on every request.
• Server-Side Rendering: The HTML is generated on each request, providing up-to-date content but potentially slower load times.

5. How do you create dynamic routes in Next.js?

Dynamic routes can be created by using square brackets in the pages directory. For example, a file named [id].js can be used to create routes like /1, /2, etc.

6. What are API routes in Next.js?

API routes are an easy way to build your API directly within a Next.js application. They are created in the pages/api directory and can return data in various formats (JSON, text, etc.).

7. How can you perform data fetching in Next.js?

Data fetching in Next.js can be done using:

• getStaticProps for Static Generation
• getServerSideProps for Server-Side Rendering
• getStaticPaths for dynamic SSG routes

8. What is the purpose of getStaticProps?

getStaticProps is a function used to fetch data at build time for static pages. It runs at build time and returns an object with props that can be used in the component.

9. What is Image Optimization in Next.js?

Next.js provides an Image component that allows you to automatically optimize images, serving them with the best format and size for user devices, thereby improving performance.

10. What is the purpose of getServerSideProps?

getServerSideProps is used for Server-Side Rendering. It runs on every request and allows you to fetch data that is rendered on the server before sending it to the client.

11. How does Next.js improve SEO?

Next.js improves SEO by enabling Server-Side Rendering and Static Generation, allowing crawlers to access fully-rendered HTML. Built-in support for dynamic meta tags and Open Graph tags also enhances SEO.

12. What is the purpose of _app.js in Next.js?

_app.js is a custom App component in Next.js that allows you to override the default App component, making it possible to persist layout between page changes and keep state.

13. How can you deploy a Next.js application?

Next.js applications can be deployed on platforms like Vercel, Netlify, or any platform that supports Node.js. Vercel is particularly optimized for Next.js.

14. What are environment variables in Next.js?

Environment variables in Next.js are used to pass sensitive data, like API keys, to the application at build time. They can be stored in an .env.local file.

15. How do you navigate between pages in Next.js?

Navigation between pages in Next.js can be done using the Link component provided by Next.js, which allows for client-side navigation.

16. What is the difference between Link and NavLink in Next.js?

In Next.js, there isn't a NavLink component by default; you only have the Link component. However, NavLink is often used in other libraries like React Router for active link styling.

17. How do you implement authentication in Next.js?

Authentication in Next.js can be implemented using libraries like NextAuth.js or by creating custom authentication solutions.

18. What is Incremental Static Regeneration (ISR)?

ISR allows you to update static pages after the build time without needing to rebuild the entire site. You can specify a revalidation time in getStaticProps.

19. How does Next.js handle CSS styles?

Next.js supports CSS Modules, global styles, and CSS-in-JS solutions. CSS Modules are enabled by default and allow for scoped styles for components.

20. What is the importance of the key prop in React?

The key prop is essential for React to identify which items have changed, been added, or been removed, helping optimize re-renders in lists.

21. What performance optimizations does Next.js provide?

Next.js provides:

• Automatic Code Splitting
• Static Generation
• Server-Side Rendering
• Image Optimization
• Pre-fetching of linked pages

22. How can you use middleware in Next.js?

Middleware in Next.js can be used to run custom code before a request is completed, allowing for tasks like authentication and logging.

23. What is React Strict Mode, and how can you enable it in Next.js?

React Strict Mode is a tool for highlighting potential problems in an application. It can be enabled in Next.js by wrapping the main component in <React.StrictMode> in _app.js.

24. Can you explain the function of the static folder in Next.js?

The public folder in Next.js is where you can store static assets such as images or favicon, which can be directly accessed at the root URL.

25. How do you handle form submission in Next.js?

Forms can be handled using local state and events in React. You can handle the form submission in an event handler and make API calls to process the data.

26. What is the purpose of Head component in Next.js?

The Head component allows you to modify the <head> of your document, enabling dynamic updates for metadata and links.

27. How can you maintain global state in Next.js?

Global state can be maintained using state management libraries like Redux, Context API, or libraries specifically designed for React like Recoil.

Summary

22 Additional Next.js Interview Questions You Can Ask Candidates

If you're looking for more questions, we have you covered. Below, you'll find 22 additional interview questions specifically for Next.js roles.

1. What strategies do you use to optimize Next.js application performance?
2. How does the fallback feature work with getStaticPaths?
3. Describe how you would implement internationalization in a Next.js app.
4. Explain the use of useEffect in Next.js.
5. How do you create a custom 404 page in Next.js?
6. Discuss the use of TypeScript in Next.js projects.
7. How can you share code between server and client in Next.js?
8. What is React.lazy, and how can it be used in Next.js?
9. How do you handle errors in a Next.js application?
10. Can you explain the concept of React Context and how it fits in Next.js?
11. Describe how Next.js handles prefetching of linked pages.
12. How would you implement pagination in a Next.js application?
13. What is the role of the _document.js file in Next.js?
14. How can you customize the server in a Next.js app?
15. What is the purpose of the .next directory in Next.js?
16. Explain how to manage state in forms within Next.js.
17. How do you enable AMP support in Next.js?
18. What is SWR, and how is it relevant to Next.js?
19. Describe the process for adding middleware in Next.js.
20. How can you implement a loading spinner or skeleton screen in Next.js?
21. Describe the process of creating a plugin for Next.js.
22. How do you implement a theme switcher in a Next.js application?

Hire top Next.js talent with confidence

To secure the best candidates for your Next.js development roles, implement a skills-first hiring strategy that includes practical coding tests and structured interviews.

Above, you'll find a thorough collection of 49 Next.js interview questions designed to enhance your interview preparation process. For more resources, explore our test library to discover tailored assessments for each Next.js position you aim to fill – and start your recruitment journey.

Schedule a free 30-minute demo to discuss your hiring needs with one of our specialists – or get started by signing up for our Forever free plan to experience our platform firsthand.