What is Node.js?

Node.js is an open-source, cross-platform JavaScript runtime environment that allows you to run JavaScript outside the browser. It is built on Chrome's V8 engine and is designed for building scalable network applications.

What is a runtime environment?

A runtime environment is a software layer that provides the necessary resources (such as memory management, I/O operations, and execution context) for a program to run. In the case of Node.js, it provides an environment where JavaScript code can execute outside the browser, using system-level features like file handling, networking, and databases.

Components of a Browser JavaScript Runtime

  1. JavaScript Engine – Executes JavaScript code (e.g., V8 for Chrome, SpiderMonkey for Firefox, JavaScriptCore for Safari).
  2. Web APIs – Provides features like DOM Manipulation, Fetch API, setTimeout, console.log, and more.
  3. Event Loop – Handles asynchronous operations and ensures smooth execution of non-blocking tasks.
  4. Callback Queue – Stores asynchronous tasks (like timers and event listeners) to be processed by the event loop.
  5. Microtask Queue – Handles promises and other high-priority asynchronous operations before moving to the callback queue.
  6. Rendering Engine – Updates the UI based on changes in the DOM and CSS.
  7. Heap & Stack – Manages memory allocation and function execution.

Who Created Node.js?

Node.js was created by Ryan Dahl in 2009. He developed it to improve the way JavaScript handled asynchronous operations, particularly for building scalable, non-blocking server applications.

Capabilities Node.js Added to JavaScript

Before Node.js, JavaScript was mainly used in browsers. Node.js extended JavaScript’s capabilities by allowing it to run outside the browser with features like:

  1. File System Access – Read, write, and manipulate files (fs module).
  2. Networking – Build web servers, handle HTTP, TCP, UDP, and WebSocket connections (http, net, and dgram modules).
  3. Process Management – Execute system commands, spawn child processes (child_process module).
  4. Asynchronous & Non-blocking I/O – Handles I/O operations efficiently using event-driven architecture.