Top MERN Stack Interview Questions

Top MERN Stack Interview Questions

Q: What is MERN stack?

A: MERN stack is a set of technologies that are used to develop web applications. It stands for MongoDB, Express.js, React.js, and Node.js.

Q: What is MongoDB?

A: MongoDB is a document-based NoSQL database that is used to store data in a JSON-like format. It is highly scalable and provides features like indexing, replication, and sharding.

Q: What is Express.js?

A: Express.js is a web application framework for Node.js. It provides a set of features for building web applications, including routing, middleware, and templates.

Q: What is React.js?

A: React.js is a JavaScript library for building user interfaces. It provides a declarative approach to building components, which makes it easier to create complex UIs.

Q: What is Node.js?

A: Node.js is a JavaScript runtime environment that allows developers to run JavaScript on the server-side. It provides an event-driven, non-blocking I/O model, which makes it highly scalable.

Q: What is JSX?

A: JSX is a syntax extension for JavaScript that allows you to write HTML-like code in your React components. It allows you to combine HTML and JavaScript code in a single file.

Q: What is Babel?

A: Babel is a tool that allows you to write modern JavaScript code and convert it to a version that is compatible with older browsers. It also allows you to use features like JSX and ES6 modules.

Q: What is Webpack?

A: Webpack is a module bundler that allows you to bundle your JavaScript, CSS, and other assets into a single file. It also provides features like code splitting and hot module replacement.

Q: What is Redux?

A: Redux is a state management library for React. It provides a predictable way to manage the state of your application, which makes it easier to debug and test.

Q: What is the difference between state and props in React?

A: State and props are both used to store data in a React component, but they serve different purposes. State is used to store data that can change over time, while props are used to pass data from a parent component to a child component.

Q: What is a virtual DOM in React?

A: The virtual DOM is a concept in React that allows the library to optimize updates to the UI. Instead of directly updating the real DOM, React creates a virtual representation of the UI, which it can update more efficiently.

Q: How do you handle form data in React?

A: Form data in React can be handled using the controlled component pattern. This involves storing the form data in the component's state and updating it as the user interacts with the form.

Q: What is a higher-order component in React?

A: A higher-order component (HOC) is a function that takes a component as its argument and returns a new component with additional functionality. HOCs are used to add features like data fetching, authentication, and logging to a component.

Q: What is a callback function in Node.js?

A: A callback function is a function that is passed as an argument to another function and is called when the other function has completed its task. Callbacks are used extensively in Node.js for asynchronous programming.

Q: What is the difference between synchronous and asynchronous programming in Node.js?

A: Synchronous programming involves blocking the execution of the program until a task is complete, while asynchronous programming allows the program to continue executing while a task is being performed. Asynchronous programming is more commonly used in Node.js because it allows for better performance and scalability.

Q: What is middleware in Express.js?

A: Middleware is a function that sits between the request and response objects in an Express.js application. It can be used to perform tasks