mern stack interview questions

Top 10 Most Asked MERN Stack Interview Questions With Answers

October 10, 2023

Are you preparing for a MERN stack interview question? If so, you’re likely feeling a mix of excitement and nerves. Understanding the ins and outs of the MERN stack is crucial for any web developer looking to stay ahead of the curve. While there’s no way to predict every question you might encounter during an interview, there are some key topics you can focus on to help you feel more confident and prepared. In this guide, we’ll cover some of the most common MERN stack developer interview questions and provide tips for answering them effectively. To learn more, scroll down.

Who is a Full Stack Developer?

A Full Stack Developer is an expert in multiple programming languages and frameworks for front-end and back-end development. He can handle the entire web application development process. He can design the user interface, write server-side code, and deploy the application. A Full Stack Developer understands databases, APIs, and web servers well. He is always up-to-date with the latest trends and technologies in the field.

Who is a Mern Stack Developer?

A Mern Stack Developer uses a combination of technologies such as MongoDB, Express, React, and Node.js to build robust and scalable web applications. He has a profound understanding of both front-end and back-end technologies. He can seamlessly integrate them to create high-performance applications to meet the client’s needs. A Mern Stack Developer is familiar with JavaScript, HTML, and CSS. He has experience working with databases and cloud-based technologies.

What are the Differences between a MERN Stack and a Full Stack Developer?

As a user, the main difference between a MERN stack developer and a full stack developer is the technology they specialize in. A MERN stack developer focuses on MongoDB, ExpressJS, ReactJS, and NodeJS, while a full stack developer is skilled in front-end and back-end technologies. Full stack developers have a broader range of skills and can work with more technologies, while MERN stack developers have a more specialized skill set. However, both types of developers are essential for building robust and efficient web applications.

MERN Stack Developer Interview Questions and Answer

Question 1: How does React work?

Answer: React is a JavaScript library. It is used for building user interfaces. It uses a virtual DOM. It is a lightweight representation of the actual DOM. When a user interacts with a React component, React updates the virtual DOM. It then compares the new virtual DOM with the old one and updates the actual DOM only with the changes. It makes React very fast and efficient. React is also based on a component-based architecture. It makes it easy to reuse code and build complex UIs.

Question 2: What are the key skills and technologies required for a full-stack developer to start a project from scratch?

Answer: As someone with experience working with full-stack developers, several essential skills and technologies are required to start a project from scratch. First and foremost, a full-stack developer should have a strong understanding of both front-end and back-end development. It means proficiency in languages and frameworks such as HTML, CSS, JavaScript, jQuery, AngularJS, ReactJS, Node.js, and Ruby on Rails. In addition to technical skills, a full-stack developer should possess excellent problem-solving, communication, and project management abilities. They should be able to work collaboratively with other team members, prioritize tasks effectively, and deliver quality code on time. Finally, full-stack developers must stay up-to-date with the latest technologies and trends to ensure their skills remain relevant and valuable.

Question 3: What are react hooks?

Answer: React hooks are a React library feature that allows developers to use state and other React features without having to write class components. They were introduced in React version 16.8 and have since become a popular and powerful tool for building React applications. Hooks allow developers to add state, effects, and other features to functional components, making them more powerful and easier to work with than ever before. With hooks, developers can write cleaner, more maintainable code that is easier to reason about and debug. Overall, React hooks are a great addition to the React library, making it easier and more enjoyable to work with.

Question 4: Explain props in react?

Answer: In React, props (short for properties) are used to pass data from one component to another. It allows for a more modular and reusable code structure. Props are read-only, meaning the receiving component cannot modify them. Instead, the component that passes the props is responsible for updating or changing the data. Props can be any data type, including arrays, objects, strings, and numbers. They are passed down the component tree, from parent to child, and can be accessed using the “this.props” syntax in class components or by destructuring in functional components.

Question 5: What is MongoDB, and how is it different from traditional relational databases?

Answer: MongoDB is a popular NoSQL database that stores data in a document-oriented format. Unlike traditional relational databases, MongoDB doesn’t rely on tables with pre-defined columns and relationships between them. Instead, data is stored in flexible JSON-like documents with varying structures. It allows for more effortless scalability and faster data retrieval, making it a popular choice for modern web and mobile applications. Additionally, MongoDB supports horizontal scaling, sharding, and replication, which can help with high availability and fault tolerance. MongoDB is a more flexible and scalable alternative to traditional relational databases.

Question 6: Explain the role of Express.js in the MERN stack

Answer: Express.js is a web application framework used in the MERN stack. It is responsible for handling the server-side logic of web apps built using the MERN stack. Express.js provides tools and features that make building scalable and efficient web applications easier. It is built on Node.js and allows developers to create APIs, handle HTTP requests, and manage server-side routing. Express.js is crucial in the MERN stack and will enable developers to build fast and reliable web applications.

Question 7: What is React.js, and why is it used in the MERN stack?

Answer: React.js is a JavaScript library used in the MERN stack. It lets developers create dynamic user interfaces easily. React.js is popular because it provides for creating reusable components, making it easier to manage and maintain complex applications. Additionally, it offers high flexibility and performance, making it ideal for building modern web applications. Overall, React.js is an essential component of the MERN stack, and developers highly value its versatility and ease of use.

Question 8: What is Node.js, and how does it fit into the MERN stack?

Answer: Node.js is a JavaScript runtime environment. It lets developers run JavaScript code outside a web browser. It fits into the MERN stack as the “N” in the acronym for MongoDB, Express, React, and Node.js. Node.js acts as the backend server in this stack, allowing for efficient communication between the front-end React application and the MongoDB database. Its event-driven, non-blocking I/O model makes it popular for building scalable and high-performing web applications.

Question 9: Explain the concept of JSX in React.

Answer: JSX is a syntax extension used in React. It lets developers write HTML-like code within JavaScript. It simplifies the creation of complex UI components by enabling developers to use familiar HTML elements and attributes in their code. JSX is not a requirement for React, but it is a recommended approach as it helps maintain the separation of concerns between the presentation and logic layers. Using JSX, developers can build dynamic, interactive, and reusable user interfaces more efficiently and intuitively.

Question 10: What is Babel, and why is it commonly used in React projects?

Answer: Babel is a JavaScript compiler. It is used in React projects. It allows developers to write modern JavaScript code while ensuring it is compatible with older browsers. Babel transforms the latest features of JavaScript into a version that can be run on any browser, making it easier for developers to write code that works seamlessly across different platforms. With Babel, developers can write code that is more concise and expressive, improving the overall quality of the codebase.


1) Is MERN stack easy for beginners?

MERN stack is a preferred choice for building web applications, but it can be overwhelming for beginners. It’s essential to have a good understanding of JavaScript and React before diving into the MERN stack. Once you have a solid foundation, you can learn about Node.js and MongoDB.

2) Why should I choose MERN stack?

MERN stack is highly scalable and flexible. It allows you to build complex, large-scale web applications that handle heavy traffic. All-inclusive stack that includes MongoDB, Express, React, and Node.js. It means that you can develop the entire web application using a single language, JavaScript.

3) How do you explain a MERN stack project?

A MERN stack project is a web development project that utilizes four key technologies: MongoDB, Express.js, React.js, and Node.js. Using these technologies together, developers can create scalable and efficient web applications that are fast, responsive, and easy to maintain.

4) Is MERN good for the future?

Yes, MERN is an excellent choice for building web applications in the future. It is a popular and influential technology stack that includes MongoDB, Express, React, and Node.js, which work seamlessly together to provide a modern and scalable solution for developing web applications.

5) What are the features of the MERN stack?

The MERN stack consists of four main components: MongoDB, Express.js, React.js, and Node.js. Each component plays a crucial role in the development process. Together, these components form a comprehensive and dynamic full-stack development environment ideal for building modern web applications.

You can Also Read: