Top 30+ Node js Interview Questions and Answers 2025

That’s why we’ve put together this guide to the most common full-stack developer interview questions. In Node.js, non-blocking refers to the ability of the runtime environment to execute multiple tasks simultaneously without waiting to complete one task before starting the next. This is achieved through the use of asynchronous I/O operations, which allow Node.js to handle multiple requests concurrently. Control flow in Node.js refers to the sequence in which statements and functions are executed. It manages the order of execution, handling asynchronous operations, callbacks, and error handling to ensure smooth program flow.

• Node.js is the best choice for asynchronous programming Python is not the best choice for asynchronous programming.
• Surveys consistently show NodeJS leading the way in developer preferences for backend frameworks.
• Architecture patterns allow you to express and define a structural schema for software systems.
• CSS selectors are patterns used to select and style specific elements in an HTML document.
• Another key aspect is adhering to established coding standards and conventions within the team or organization.

Node.js and Databases

Basically, Node.js is based on an event-driven architecture where I/O runs asynchronously making it lightweight and efficient. It is being used in developing desktop applications as well with a popular framework called electron as it provides API to access OS-level features such as file system, network, etc. Code reviews are a critical part of software development, ensuring that the codebase remains clean, efficient, and free of bugs. By asking this question, interviewers want to see that you recognize and value the importance of collaboration and teamwork, as well as your ability to provide constructive feedback to your peers.

• Interviewers ask this question to evaluate your understanding of best practices in coding and your commitment to writing high-quality code.
• Memory leaks usually happen when unused resources (e.g., DOM elements, event listeners, or data structures) are not properly released, causing unnecessary memory consumption.
• The Web, also known as the World Wide Web (WWW), is a collection of web pages, images, videos, and other resources connected through links.
• APIs (Application Programming Interfaces) are sets of rules and protocols that define how software programs or devices can communicate with each other.
• This allows scripts that are run on a browser client to interact with and access resources from other origins.
• The first argument is always an error object that the programmer has to check if something went wrong.
• If we can swap back-and-forth between these expressions anytime, anywhere, without altering their meaning or output, then an expression is referentially transparent.

What is a first class function in Javascript?

Your response will indicate your familiarity with these principles and your ability to thrive in a fast-paced, collaborative setting—qualities that are essential for success as a full stack developer. Refactoring legacy code is a common challenge for developers, and interviewers want to know how you approach this task. They’re interested in your ability to identify issues, employ best practices, and adapt to new technologies while maintaining the stability of existing systems. Sharing your experience with refactoring legacy code demonstrates your problem-solving skills, technical expertise, and ability to work with complex and potentially outdated systems. Clean, maintainable, and scalable code is essential for a successful software project, especially when working in a team environment. Interviewers ask this question to evaluate your understanding of best practices in coding and your commitment to writing high-quality code.

Explain some of the cluster methods in Node.js

Full Stack Development is a crucial aspect of modern web applications, involving both frontend and backend technologies to build dynamic, scalable, and high-performance applications. To overcome these challenges, I first spent time analyzing the codebase and creating a detailed map of its Coding components and their relationships. This helped me identify critical areas that needed immediate attention and potential bottlenecks in the system. Next, I collaborated with my team members who had experience working with the older technology stack to gain insights into the original design decisions and any known issues.

Ques 37: What are Lifecycle Methods in React?

Each organization has its unique way of getting new applications into the production environment. Most organizations follow the standard deployment and release strategies such as Blue-Green and Rolling Deployment. It is a collection of JavaScript-based technologies for developing web applications. Despite being a stack of different technologies, all of them are based on the JavaScript language.

How does NodeJS handle asynchronous error handling?

• Same-origin policies restrict the ability of a website to access resources outside of its source domain.
• It follows a unidirectional data flow and uses actions, reducers, and stores.
• As a full stack developer on a Scrum team, I participated in daily stand-up meetings where we discussed our progress, any roadblocks, and planned our work for the day.
• So if it’s so popular and in demand, this can be a great programming language to learn.
• Keys in React lists help identify elements uniquely, improving rendering efficiency.
• Highlights the candidate’s experience in documenting Node.js processes and their ability to apply best practices in recordkeeping.

It was widely accepted as a backend framework and comes to the top, 2nd year in a row in 2020 of StackOverflow survey. 13+ Yrs Experienced Career Counsellor & Skill Development Trainer | Educator | Digital & Content Strategist. Helping freshers and graduates make sound career choices through practical consultation.

Node provides a single thread to programmers so that code can be written easily and without bottleneck. Node internally uses multiple POSIX threads for various I/O operations such as File, DNS, Network calls etc. A potential employer doesn’t expect applicants to know everything, whether they’re freshers or experienced. However, a well-prepared and enthusiastic candidate will undoubtedly stand out. In a full stack developer interview, candidates should be able to demonstrate excellent organizational skills and precision in their work. Libuv is a multi-platform C library that provides support for asynchronous I/O-based JavaScript Full-stack developer (Node.jsReact.js) job operations such as file systems, networking, and concurrency.