Node.js is a popular open-source, cross-platform runtime environment that allows developers to build server-side applications using JavaScript. With the rise in demand for Node.js developers, it has become increasingly important for aspiring candidates to be well-prepared for technical interviews. To help you ace your Node.js interview in 2024, here is a comprehensive list of the top 100+ Node.js interview questions and answers.
1. What is Node.js?
Node.js is a runtime environment that allows developers to run JavaScript code on the server-side.
2. What are the key features of Node.js?
Node.js is non-blocking, event-driven, and single-threaded, which allows for handling a large number of concurrent connections efficiently.
3. What is npm?
npm is Node Package Manager, which is used to install, manage, and publish Node.js packages.
4. What is the difference between process.nextTick() and setImmediate()?
process.nextTick() is used to schedule a callback function to be invoked in the next iteration of the event loop, while setImmediate() is used to schedule a callback function to be invoked in the current iteration of the event loop.
5. Explain the Event Loop in Node.js.
The Event Loop in Node.js is a mechanism that allows for handling asynchronous operations efficiently by executing callback functions when certain events occur.
6. What is callback hell?
Callback hell is a situation where multiple nested callback functions make the code difficult to read and maintain. It can be avoided by using promises or async/await.
7. What is a Promise in Node.js?
A Promise is an object that represents the eventual completion or failure of an asynchronous operation.
8. How do you handle errors in Node.js?
Errors in Node.js can be handled using try/catch blocks, error-first callbacks, or promises.
9. What is middleware in Express.js?
Middleware in Express.js is a function that has access to the request and response objects and can modify them before passing them to the next middleware function in the chain.
10. What is the difference between res.send() and res.json() in Express.js?
res.send() sends a plain text response, while res.json() sends a JSON response.
11. What is RESTful routing?
RESTful routing is a design pattern for creating web services that adhere to the principles of Representational State Transfer (REST).
12. What is streaming in Node.js?
Streaming in Node.js is a mechanism that allows for reading and writing data in chunks rather than loading the entire content into memory.
13. What is clustering in Node.js?
Clustering in Node.js is a technique that allows for creating multiple instances of a Node.js process to take advantage of multi-core CPUs.
14. How do you debug Node.js applications?
Node.js applications can be debugged using the built-in debugger, the Node.js Inspector, or third-party tools like Visual Studio Code.
15. How do you profile Node.js applications?
Node.js applications can be profiled using the built-in profiler, the –prof flag, or third-party tools like New Relic or AppDynamics.
16. What is the difference between setTimeout() and setInterval()?
setTimeout() is used to execute a callback function once after a specified delay, while setInterval() is used to execute a callback function repeatedly at a specified interval.
17. What is the purpose of the global object in Node.js?
The global object in Node.js provides access to global variables, such as process, console, and Buffer.
18. How do you handle file uploads in Node.js?
File uploads in Node.js can be handled using middleware like multer or the built-in fs module.
19. What is a closure in JavaScript?
A closure is a function that has access to its own scope, the outer function’s scope, and the global scope.
20. What is the difference between var, let, and const in JavaScript?
var is function-scoped, while let and const are block-scoped. let can be reassigned, while const is immutable.
21. What is the purpose of the EventEmitter class in Node.js?
The EventEmitter class in Node.js is used to implement custom events and handle event-driven programming.
22. What is CORS?
CORS (Cross-Origin Resource Sharing) is a security feature that allows or restricts access to resources across different origins.
23. How do you secure Node.js applications?
Node.js applications can be secured by using HTTPS, content security policies, CSRF protection, input validation, and authentication mechanisms.
24. What is JWT?
JWT (JSON Web Token) is a compact, self-contained token that can be used for securely transmitting information between parties.
25. What is the difference between hashing and encryption?
Hashing is a one-way function that converts data into a fixed-size string, while encryption is a two-way function that converts data into a ciphertext that can be decrypted.
26. What is the purpose of the Buffer class in Node.js?
The Buffer class in Node.js is used to handle raw binary data.
27. How do you handle memory leaks in Node.js?
Memory leaks in Node.js can be handled by using a memory profiler, monitoring memory usage, and optimizing garbage collection.
28. How do you scale Node.js applications?
Node.js applications can be scaled horizontally by adding more instances or vertically by increasing the resources of a single instance.
29. What is the difference between a monolithic and microservices architecture?
A monolithic architecture consists of a single codebase, while a microservices architecture consists of multiple smaller services that communicate with each other.
30. What is PM2?
PM2 is a process manager for Node.js applications that provides features like clustering, load balancing, and monitoring.
These are just a few of the top 100+ Node.js interview questions and answers for 2024. By thoroughly preparing for your Node.js interview, you can showcase your knowledge and skills to potential employers and secure your dream job in the field of Node.js development. Good luck!
