Top Node.js interview questions that are often asked to freshers

Nail your Node.js interview with these 15 handpicked questions for freshers. Boost your confidence and stand out in the crowd.

These are indeed common Node.js interview questions for freshers. Here are concise answers to each:

1. What is Node.js?

• Node.js is an open-source, server-side JavaScript runtime environment that executes JavaScript code outside of a web browser. It allows developers to build scalable, high-performance network applications.

2. What is npm? How do you use it?

• npm (Node Package Manager) is the default package manager for Node.js. It allows developers to install, share, and manage dependencies in Node.js projects. You can use it via the command line interface with commands like npm install, npm init, etc.

 3. What is event-driven programming?

• Event-driven programming is a programming paradigm where the flow of the program is determined by events such as user actions, sensor outputs, or messages from other programs or threads. In Node.js, many operations are performed asynchronously and are based on events.

4. Explain the concept of non-blocking I/O in Node.js.

• Non-blocking I/O means that Node.js can perform other operations while waiting for I/O operations to complete. It allows Node.js to handle multiple connections efficiently without blocking the execution of other code.

5. How does Node.js handle concurrency?

• Node.js handles concurrency through event-driven architecture and asynchronous I/O operations. It utilizes a single-threaded event loop to handle multiple connections concurrently.

6. What is the purpose of package.json in Node.js projects?

• The package.json file contains metadata about a Node.js project, such as its name, version, dependencies, scripts, etc. It also defines project settings and configurations.

7. How do you handle errors in Node.js?

• Errors in Node.js can be handled using try-catch blocks for synchronous code and error-first callbacks or promises for asynchronous code. Additionally, you can use tools like try...catch and error middleware in frameworks like Express.js.

8. What is a callback function? Can you provide an example?

• A callback function is a function passed as an argument to another function, which will be invoked later when a particular event occurs. Example: 

9. Explain the difference between synchronous and asynchronous code in Node.js.

• Synchronous code executes sequentially, blocking further execution until it completes. Asynchronous code allows the program to continue executing while waiting for I/O operations or other tasks to complete.

10. What is the difference between require() and import in Node.js?

• require() is the traditional way to import modules in Node.js, while import is the ES6 syntax for importing modules. import supports static analysis, tree-shaking, and other ES6 features.

11. How can you create a simple HTTP server in Node.js?

• You can create a simple HTTP server using the built-in http module in Node.js. Here's an example:

12. What is middleware in the context of Express.js?

• Middleware in Express.js are functions that have access to the request object (req), the response object (res), and the next middleware function in the application's request-response cycle. They can modify request and response objects, terminate the request-response cycle, or call the next middleware function.

13. Explain the concept of streams in Node.js.

• Streams in Node.js are objects that allow you to read data from a source or write data to a destination continuously. They enable efficient handling of large amounts of data by processing it in chunks rather than loading it all into memory at once.

14. How do you debug Node.js applications?

• Node.js applications can be debugged using built-in debugging tools like console.log, debugger statement, or using third-party debugging tools like node-inspect, Chrome DevTools, or IDEs like Visual Studio Code with built-in debuggers.

15. What tools or frameworks would you use alongside Node.js for building web applications?

• Alongside Node.js, developers often use frameworks like Express.js for building web applications due to its simplicity and flexibility. Other tools and frameworks commonly used include MongoDB or MySQL for databases, Socket.io for real-time communication, and React or Angular for frontend development, among others.

These questions cover a range of fundamental concepts in Node.js and related technologies that freshers are expected to understand for interviews.

Conclusion:

The most important Node.js interview questions give an extensive review of important concepts for beginners. To be successful in interviews and create reliable Node.js applications, it is necessary to understand Node.js, npm, event-driven programming, non-blocking I/O, concurrency, package.json, error handling, callbacks, synchronous versus asynchronous code, module imports, HTTP server creation, Express.js middleware, streams, debugging techniques, and auxiliary tools like frameworks and databases. Building an understanding of these ideas provides beginners with strong foundations on which to establish their careers in Node.js programming.