‹ NodeJS Interview ☰
NodeJS Basics NodeJS Environment NodeJS Architecture NodeJS Filesystem Module NodeJS HTTP Module NodeJS Callbacks NodeJS Promises NodeJS Async And Await NodeJS User Authentication NodeJS Security NodeJS Websockets NodeJS Socket.Io NodeJS Error Handling NodeJS Debugging NodeJS Streams NodeJS Event Emitters NodeJS Rest APIs NodeJS GraphQL NodeJS File Handling NodeJS Microservices Architecture NodeJS Deployment NodeJS Scaling Applications NodeJS Event Loop NodeJS Child Processes NodeJS Worker Threads NodeJS And Mongodb NodeJS And SQL Database

‹ NodeJS Interview

NodeJS Basics NodeJS Environment NodeJS Architecture NodeJS Filesystem Module NodeJS HTTP Module NodeJS Callbacks NodeJS Promises NodeJS Async And Await NodeJS User Authentication NodeJS Security NodeJS Websockets NodeJS Socket.Io NodeJS Error Handling NodeJS Debugging NodeJS Streams NodeJS Event Emitters NodeJS Rest APIs NodeJS GraphQL NodeJS File Handling NodeJS Microservices Architecture NodeJS Deployment NodeJS Scaling Applications NodeJS Event Loop NodeJS Child Processes NodeJS Worker Threads NodeJS And Mongodb NodeJS And SQL Database

NodeJS Basics

What is Node.js?

Node.js is a JavaScript runtime environment built on Chrome’s V8 engine. It allows developers to use JavaScript for server-side scripting, enabling the development of scalable network applications. Node.js is event-driven, non-blocking, and asynchronous, making it suitable for I/O-intensive tasks like web servers and APIs.

What makes Node.js different from traditional server-side technologies?

Node.js is single-threaded and uses an event-driven, non-blocking I/O model. This contrasts with traditional server-side platforms that typically handle multiple threads. Node.js’s asynchronous nature allows it to handle many concurrent connections efficiently without the overhead of managing multiple threads.

What is the V8 engine in Node.js?

The V8 engine is an open-source JavaScript engine developed by Google. It compiles JavaScript to native machine code, making it extremely fast. Node.js uses the V8 engine to execute JavaScript code on the server-side.

What is the main use case of Node.js?

Node.js is primarily used for building fast, scalable network applications. It is particularly suited for real-time applications such as chat apps, collaborative tools, streaming services, and APIs.

How does Node.js handle asynchronous operations?

Node.js handles asynchronous operations using a non-blocking event loop. When an asynchronous operation (such as reading a file) is initiated, Node.js continues executing other code while the operation completes in the background. Once the operation is finished, a callback function is triggered, allowing the program to handle the result.

What is the Node.js event loop?

The event loop is a core component of Node.js that handles asynchronous operations. It allows Node.js to perform non-blocking I/O operations by managing callbacks and events. The event loop constantly checks for new tasks to execute, handling I/O operations, timers, and callbacks in a continuous cycle.

What are some advantages of using Node.js?

Advantages of Node.js include:

  • High performance due to the V8 engine and asynchronous I/O.
  • Single programming language for both frontend and backend (JavaScript).
  • Large ecosystem of libraries through npm (Node Package Manager).
  • Suitable for real-time applications and APIs.
  • Scalable due to its event-driven architecture.

What is npm (Node Package Manager)?

npm is the default package manager for Node.js. It allows developers to install, share, and manage libraries (also called packages) in their Node.js projects. npm provides access to a vast ecosystem of open-source tools and modules, simplifying the development process.

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

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

const http = require('http');
const server = http.createServer((req, res) => {
   res.statusCode = 200;
   res.setHeader('Content-Type', 'text/plain');
   res.end('Hello, World!');
});
server.listen(3000, () => {
   console.log('Server running at http://localhost:3000/');
});

This code creates an HTTP server that listens on port 3000 and responds with 'Hello, World!'.

Is Node.js single-threaded or multi-threaded?

Node.js is single-threaded in nature. However, it uses multiple threads under the hood to perform asynchronous I/O operations via the 'libuv' library. The main event loop remains single-threaded, but non-blocking tasks (such as file I/O) are handled by worker threads in the background.

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