Node JS Interview Questions and Answers
Prepare Node JS interview questions with clear answers. Covers core concepts, APIs, async handling and real backend scenarios for freshers.
Node Basics
Q. What is Node JS?
Node JS is a runtime environment that allows JavaScript to run on the server side.
Q. What are the features of Node JS?
Node JS is fast, scalable, non blocking, and uses event driven architecture.
Q. What is npm?
npm is a package manager used to install and manage dependencies in Node JS projects.
Event Loop and Async
Q. What is the event loop in Node JS?
The event loop handles asynchronous operations by managing callbacks and executing them without blocking the main thread.
Q. What is a callback function?
A callback is a function passed as an argument to another function and executed after completion.
Q. What is a promise?
A promise represents a value that may be available now, later, or never.
Q. What is async and await?
Async and await simplify handling asynchronous code by making it look synchronous.
Express and API
Q. What is Express JS?
Express is a web framework for Node JS used to build APIs and web applications easily.
Q. What is routing in Express?
Routing defines how an application responds to different URL requests.
Q. What is middleware?
Middleware functions process requests and responses in the application pipeline.
Q. What is a REST API?
A REST API allows communication between client and server using HTTP methods like GET, POST, PUT, and DELETE.
Database Integration
Q. What is MongoDB?
MongoDB is a NoSQL database used to store data in JSON like format.
Q. What is Mongoose?
Mongoose is an ODM library used to interact with MongoDB in Node JS.
Q. What are CRUD operations?
CRUD stands for Create, Read, Update, and Delete operations on data.
Security and Performance
Q. How is error handling done in Node JS?
Error handling is done using try catch blocks and middleware for handling errors globally.
Q. Why is Node JS considered scalable?
Node JS handles multiple requests efficiently using non blocking I O and event driven architecture.
Q. How do you secure a Node JS application?
Security can be improved using validation, authentication, and avoiding vulnerabilities like injection attacks.
Q. How do you improve performance in Node JS?
Performance can be improved by using caching, clustering, and optimizing code.
Tips to Crack Technical Interviews
Simple preparation tips to improve your performance across technical interviews for fresher roles.
Understand Core Concepts
Focus on event loop, async handling, and how Node works internally.
Build APIs
Practice creating APIs using Express to understand real backend flow.
Practice Async Code
Be comfortable with promises and async await for handling operations.
Explain API Flow
Be ready to explain how requests move from client to server.
Focus on Practical Usage
Real project understanding matters more than theoretical answers.
Stay Updated
Keep learning new tools and updates in Node JS ecosystem.
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