A: MERN stack is a set of technologies, including MongoDB (database), Express.js (backend framework), React (frontend library), and Node.js (JavaScript runtime).
A: MongoDB is a NoSQL database used in the MERN stack to store and manage data. It stores data in JSON-like BSON format and provides scalability and flexibility.
A: Express.js is a backend web application framework for Node.js. It simplifies the process of building robust and scalable web applications by providing a set of features and middleware.
A: React is a JavaScript library for building user interfaces. It focuses on building UI components with a one-way data flow, making it efficient and easy to manage complex UIs.
A: Node.js is a JavaScript runtime used on the server side in the MERN stack. It allows the execution of JavaScript code on the server, enabling the creation of scalable and high-performance web applications.
A: JSX (JavaScript XML) is a syntax extension for JavaScript used with React. It allows you to write HTML elements and components in a syntax similar to XML or HTML within JavaScript code.
A: React organizes UI components into a tree structure. Each component has its state and properties. React updates the UI efficiently by selectively rendering only the components affected by data changes.
A: State in React is an object that represents the dynamic data of a component. When the state changes, React re-renders the component to reflect the updated state.
A: Props (short for properties) are inputs to React components. They allow you to pass data from a parent component to a child component, enabling communication between components.
A: Node.js uses an event-driven, non-blocking I/O model. It employs callback functions and Promises to handle asynchronous operations, allowing efficient handling of multiple requests without blocking the execution of code.
A: Middleware in Express.js are functions that have access to the request, response, and next function in the application’s request-response cycle. They can perform tasks like logging, authentication, and error handling.
A: MongoDB stores data in BSON (Binary JSON) format, which is a binary-encoded serialization of JSON-like documents. Documents in MongoDB are organized into collections.
A: package.json is a file that contains metadata about a Node.js project. It includes project dependencies, scripts, version information, and other configuration details. It is crucial for managing and documenting the project.
A: The virtual DOM is a lightweight copy of the actual DOM in React. It allows React to efficiently update and render components by making minimal changes to the real DOM, reducing the need for direct manipulation.
A: React handles events using synthetic events, providing a consistent interface for handling events across different browsers. Event handlers in React are written in camelCase and passed as props to components.
A: Routing in React allows the creation of single-page applications by dynamically updating the UI based on the URL. React Router is a popular library used for implementing routing in React applications.
A: The useEffect hook in React is used for handling side effects in functional components. It replaces lifecycle methods like componentDidMount, componentDidUpdate, and componentWillUnmount.
A: To secure an Express.js application, you can use middleware like Helmet for setting HTTP headers, employ HTTPS for secure communication, implement authentication and authorization mechanisms, and sanitize input data.
A: npm (Node Package Manager) is a package manager for Node.js. It allows developers to install, share, and manage dependencies for their Node.js projects.
A: You can use the Fetch API or libraries like Axios to make HTTP requests from the React frontend to the Express.js backend. Cross-Origin Resource Sharing (CORS) should be configured on the server to handle requests from different origins.
These questions cover a range of topics related to the MERN stack, providing a foundation for beginners to understand the key concepts and technologies involved.
