Node JS Interview Questions

1.What is Node.js?

-Node.js is a JavaScript runtime built on Chrome’s V8 JavaScript engine. It enables developers to run JavaScript on the server-side and is designed to build scalable, high-performance applications.

2.What are the benefits of using Node.js?

-Some of the benefits of using Node.js include:

•        It’s fast and efficient because it uses non-blocking I/O.

•        It’s highly scalable and can handle a large number of concurrent connections.

•        It’s cross-platform and can run on Windows, macOS, and Linux.

•        It has a large and active community that contributes to the development of open-source modules and packages.

•        It’s easy to learn and has a low barrier to entry for developers familiar with JavaScript.

3.What is NPM?

-NPM (Node Package Manager) is a package manager for Node.js. It provides access to thousands of modules and packages that can be easily installed and managed for use in Node.js projects.

4.How can you handle errors in Node.js?

-Node.js provides several mechanisms for handling errors, including try-catch statements, callbacks, and event emitters. Developers can also use third-party error handling packages like express-async-errors and express-validator.

5.What is a callback function in Node.js?

-A callback function is a function passed as an argument to another function in Node.js. It’s used to handle asynchronous operations and is called when the operation completes. Callbacks are a key feature of Node.js and are used extensively in its APIs and modules.

6.What is the event loop in Node.js?

-The event loop is a key feature of Node.js that handles asynchronous operations. It continuously monitors the Node.js runtime for pending events and executes them when they occur. The event loop is what allows Node.js to handle a large number of concurrent connections without blocking I/O operations.

7.What is middleware in Node.js?

-Middleware in Node.js refers to a function that sits between the request and response objects in an HTTP request/response cycle. It can perform various tasks, such as logging, authentication, and error handling. Express.js, a popular Node.js framework, uses middleware extensively.

8.What is the difference between Node.js and AJAX?

-Node.js is a server-side runtime environment, whereas AJAX is a client-side technique for making asynchronous HTTP requests. Node.js can be used to build both server-side and client-side applications, whereas AJAX is only used on the client-side.