In the fast-paced world of web development, Node.js has become a linchpin for building robust server-side applications.

Whether you're gearing up for an interview or aiming to deepen your Node.js expertise, we've distilled the essential knowledge into 50 interview questions.

This quick guide will cover the core concepts and advanced topics, testing both your theoretical understanding and practical skills.

📌 50 Node JS Interview Questions

General Node.js Questions:

• What is Node.js, and what is it used for?
• How does Node.js handle asynchronous operations?
• Explain the Event Loop in Node.js.
• What are the advantages of using Node.js?
• How do you handle errors in Node.js?
• What is the role of the “package.json” file?
• How can you share code across multiple files in Node.js?
• What is NPM, and why is it used in Node.js?
• What are callbacks in Node.js, and how do you handle callback hell?
• How does Node.js handle multi-threading?

Module System and NPM:

• What is the CommonJS module system in Node.js?
• How do you import modules in Node.js?
• What is the difference between “require” and “import”?
• How can you create custom NPM modules and publish them?
• What is the purpose of the “package-lock.json” file?

Web Development with Node.js:

• How do you create an HTTP server in Node.js?
• Explain the role of Express.js in Node.js applications.
• What are Middleware functions in Express.js?
• How do you handle routing in an Express.js application?
• What are route parameters in Express.js?

Asynchronous Programming:

• What are Promises in Node.js, and how do they help in handling asynchronous operations?
• What is the “async/await” syntax, and how does it simplify asynchronous code?
• What are the differences between Promises and callbacks?
• How do you handle concurrency in Node.js?

RESTful APIs:

• What are RESTful APIs, and how are they implemented in Node.js?
• What are HTTP methods, and how are they used in RESTful APIs?
• How do you handle authentication and authorization in a RESTful API?

Database Integration:

• How can you connect Node.js with a MySQL database?
• How do you perform CRUD operations in MongoDB using Node.js?
• What is an Object-Relational Mapping (ORM) tool, and how does it simplify database interactions in Node.js?

Websockets and Real-Time Communication:

• What are WebSockets, and how are they different from HTTP?
• How can you implement WebSockets in a Node.js application?
• What are some use cases for real-time communication in Node.js?

Testing and Debugging:

• How do you write unit tests for Node.js applications?
• What is the purpose of the “chai” and “mocha” libraries in testing?
• How can you debug Node.js applications effectively?

Security:

• What are some common security vulnerabilities in Node.js applications, and how do you prevent them?
• How do you protect against Cross-Site Scripting (XSS) attacks?

Performance and Scalability:

• How can you optimize the performance of a Node.js application?
• What are some strategies for scaling Node.js applications to handle high traffic?

Deployment and DevOps:

• How do you deploy a Node.js application to a production server?
• What is Continuous Integration and Continuous Deployment (CI/CD), and how can it be implemented in Node.js projects?

Web Servers in Node.js:

• How can you serve static files (e.g., CSS, JavaScript) in Node.js?
• What is the purpose of reverse proxies like Nginx when deploying Node.js applications?

Streams and Buffers:

• What are streams and how are they used in Node.js?
• How do you convert data between buffers and strings in Node.js?

Memory Management:

• How does Node.js handle memory management and garbage collection?

Child Processes:

• How can you create and interact with child processes in Node.js?

Logging:

• What are some popular logging libraries used in Node.js applications?

Real-Time Applications:

• How do you build real-time applications using Node.js and technologies like Socket.io?

Please keep in mind that the following questions are designed to cover a wide range of topics related to Node.js.

However, the actual interview questions may differ depending on the specific job role and company.

To perform well in Node.js interviews, it is crucial to have a strong understanding of Node.js fundamentals, asynchronous programming, web development, and other relevant technologies.

Wishing you good luck!

Happy Coding! 🔥