As a Node JS developer with 2 years of experience, you may be looking to advance your career by landing a new job. But, to do so, you’ll need to pass an interview. Node JS interview questions can be tricky, and it’s essential to prepare yourself thoroughly. This article will provide you with a comprehensive list of Node JS interview questions that you can expect during your interview.

1. Introduction

Node JS is an open-source, cross-platform, JavaScript runtime environment that executes JavaScript code outside a web browser. It was built on Chrome’s V8 JavaScript engine and provides an event-driven, non-blocking I/O model. Node JS is popular for building scalable network applications, such as web servers and real-time applications.

2. Node JS Basics

What is Node JS?

Node JS is a server-side platform that allows developers to build server-side applications using JavaScript. It’s built on Chrome’s V8 JavaScript engine and provides an event-driven, non-blocking I/O model.

What is NPM?

NPM (Node Package Manager) is a package manager for Node JS. It allows developers to easily install, update, and remove packages (modules) from their projects.

What are the advantages of using Node JS?

Some advantages of using Node JS include:

• Scalability: Node JS applications can handle a large number of simultaneous connections with minimal overhead.
• Speed: Node JS applications are fast due to the non-blocking I/O model.
• Reusability: Node JS applications can share code between the client and server-side.
• Large community: Node JS has a large and active community, which means there is a wealth of resources available.

3. Node JS Architecture

Explain the architecture of Node JS

Node JS uses a single-threaded, event-driven architecture that allows it to handle a large number of concurrent connections with minimal overhead. Node JS uses an event loop to handle events and callbacks.

What is an event loop?

An event loop is a mechanism that allows Node JS to handle I/O operations asynchronously. It listens for events and executes callbacks when events occur.

4. Node JS Modules

What are modules in Node JS?

Modules in Node JS are reusable pieces of code that can be easily imported into other Node JS projects. Modules can be installed via NPM or can be created by the developer.

Explain the differences between require() and import() in Node JS

require() is the traditional way of importing modules in Node JS. It’s a synchronous function that loads modules at runtime. import() is a newer way of importing modules in Node JS. It’s an asynchronous function that allows for ES6 introduced import() as a new way of importing modules. Unlike require(), import() is a Promise-based asynchronous function that allows for dynamic importing of modules at runtime. It also allows for the use of destructuring and aliasing of modules.

5. Node JS Frameworks

What are some popular Node JS frameworks?

Some popular Node JS frameworks include Express, Koa, NestJS, Hapi, and Sails.

Explain the difference between Express and Koa frameworks

Express and Koa are both Node JS web application frameworks, but they differ in their approach to middleware. Express uses middleware functions in a stack-like manner, while Koa uses middleware functions in a more elegant and flexible manner, using generators or async/await functions.

6. Node JS Debugging

How do you debug Node JS applications?

Node JS provides a built-in debugger that allows developers to debug their applications using the command line. Alternatively, developers can use third-party debuggers such as Visual Studio Code or WebStorm.

What are some common errors in Node JS and how do you fix them?

Common errors in Node JS include syntax errors, runtime errors, and logic errors. Syntax errors can be fixed by reviewing and correcting the code. Runtime errors can be fixed by debugging the application and fixing the root cause of the error. Logic errors can be fixed by reviewing the code and correcting the logical flow.

7. Node JS Deployment

How do you deploy Node JS applications?

Node JS applications can be deployed using various deployment tools such as Heroku, AWS Elastic Beanstalk, or Digital Ocean. Developers can also manually deploy their applications by using a server such as Nginx or Apache.

Explain the difference between PM2 and Forever

PM2 and Forever are both process managers for Node JS applications. PM2 is a more feature-rich process manager that allows for easy deployment and scaling of Node JS applications. Forever is a simpler process manager that is easy to use and provides basic process management functionality.

8. Node JS Security

What are some security concerns with Node JS applications?

Some security concerns with Node JS applications include cross-site scripting (XSS) attacks, SQL injection attacks, and CSRF attacks.

How do you secure a Node JS application?

To secure a Node JS application, developers should follow security best practices such as using input validation, using secure coding practices, implementing access controls, and using SSL/TLS encryption.

9. Conclusion

In conclusion, Node JS is a popular and powerful server-side platform that allows developers to build scalable and efficient network applications. As a Node JS developer with 2 years of experience, it’s essential to prepare yourself thoroughly for your next interview. By familiarizing yourself with these Node JS interview questions, you can increase your chances of landing your dream job.

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