Node.js
1. What is Node.js?
Answer:
Node.js is a JavaScript runtime environment used to run JavaScript code outside the browser. It is mainly used for backend development and server-side applications. Node.js is built on Chrome’s V8 engine which makes it fast and efficient. It supports scalable and real-time web applications.
2. What is npm in Node.js?
Answer:
npm stands for Node Package Manager and is used to manage packages in Node.js projects. It helps developers install, update, and remove libraries easily. npm provides thousands of reusable packages for development. It also manages project dependencies efficiently.
3. What is Event-Driven Architecture in Node.js?
Answer:
Event-Driven Architecture in Node.js works using events and event listeners. When an action happens, an event is triggered and the related function executes automatically. This architecture helps Node.js handle multiple operations efficiently. It is widely used in real-time applications like chat systems.
4. What is Non-Blocking I/O in Node.js?
Answer:
Non-Blocking I/O allows Node.js to execute multiple operations simultaneously without waiting for one task to complete. It improves server speed and application performance. Users can continue using the application while background tasks are processed. This feature makes Node.js suitable for high-traffic applications.
5. What is Express.js?
Answer:
Express.js is a lightweight backend framework built on top of Node.js. It helps developers create APIs, routes, and web applications easily. Express.js simplifies backend coding and improves application structure. It is one of the most popular frameworks used in Node.js development.
6. What is Middleware in Express.js?
Answer:
Middleware is a function that runs between the request and response cycle in Express.js. It processes requests before sending responses to users. Middleware is commonly used for authentication, logging, and error handling. It helps improve security and code organization in applications.
7. What is the use of package.json?
Answer:
package.json is a configuration file used in Node.js projects. It stores project details, dependencies, scripts, and version information. Developers use it to manage packages and run project commands. It is one of the most important files in a Node.js application.
8. What is a Callback Function in Node.js?
Answer:
A callback function is a function passed as an argument to another function. It executes after a specific task or operation is completed. Callback functions are mainly used for asynchronous programming in Node.js. They help applications perform tasks without blocking execution.
9. What is the Event Loop in Node.js?
Answer:
The Event Loop is a mechanism that handles asynchronous operations in Node.js. It allows Node.js to execute non-blocking tasks efficiently. The Event Loop continuously checks and processes pending events and callbacks. It is one of the core features of Node.js performance.
10. What is REST API?
Answer:
REST API is a communication method used between frontend and backend applications. It uses HTTP methods like GET, POST, PUT, and DELETE for data operations. REST APIs help applications exchange data efficiently over the internet. They are widely used in modern full-stack development.
11. What is fs Module in Node.js?
Answer:
The fs module is a built-in Node.js module used for file system operations. It helps developers read, write, update, and delete files. The fs module supports both synchronous and asynchronous methods. It is commonly used for handling server-side files and data.
12. What is a Module in Node.js?
Answer:
A module is a reusable block of code in Node.js used to organize applications into separate files. Modules improve code readability and maintenance. Developers can export and import modules whenever needed. This helps create scalable and clean backend applications.
13. What is require() in Node.js?
Answer:
The require() function is used to import modules, packages, and files into a Node.js application. It helps developers reuse code across different files. require() works with the CommonJS module system in Node.js. It is commonly used for importing frameworks like Express.js.
14. What is CORS in Node.js?
Answer:
CORS stands for Cross-Origin Resource Sharing and allows applications from different origins to communicate securely. It helps connect frontend and backend applications running on different ports or domains. CORS improves API communication in MERN Stack projects. Proper CORS configuration is important for security.
15. What is JWT in Node.js?
Answer:
JWT stands for JSON Web Token and is used for secure authentication and authorization. It securely transfers user information between client and server. JWT tokens are commonly used after user login for protected routes. It improves security in modern web applications.
16. What is Authentication?
Answer:
Authentication is the process of verifying the identity of a user in an application. It ensures that only authorized users can access protected resources. Authentication commonly uses login credentials like email and password. It is important for protecting user accounts and private data.
17. What is dotenv Package?
Answer:
dotenv is a Node.js package used to manage environment variables securely. It stores sensitive information like API keys and database passwords inside a .env file. dotenv helps keep secret data separate from application code. It improves security and project configuration management.
18. What is API Routing in Express.js?
Answer:
API Routing in Express.js defines how applications respond to different client requests and URLs. It supports HTTP methods like GET, POST, PUT, and DELETE. Routing helps organize backend APIs properly in applications. Well-structured routes improve scalability and maintenance.
19. What is Async/Await in Node.js?
Answer:
Async/Await is a modern way to handle asynchronous operations in Node.js. It makes code cleaner, easier to read, and simple to debug. Async/Await works with Promises for handling async tasks. It helps avoid deeply nested callback functions.
20. What is the Difference Between Synchronous and Asynchronous Programming?
Answer:
Synchronous programming executes tasks one after another and waits for each task to finish. Asynchronous programming allows multiple tasks to run simultaneously without blocking execution. Node.js mainly uses asynchronous programming for better performance. This helps applications handle multiple users efficiently.
