Lesson 1 +10 XP

Introduction to Node.js Runtime

What is Node.js?

Node.js is an open-source, cross-platform JavaScript runtime environment built on Chrome's V8 JavaScript engine. It allows developers to run JavaScript outside the browser, enabling server-side application development.

Key Characteristics of Node.js

Single-Threaded: Node.js operates on a single main thread using event-driven execution.
Non-Blocking I/O: Input/output operations (file reads, database queries, network requests) do not block the execution of subsequent code.
Asynchronous & Event-Driven: Node.js utilizes callbacks, Promises, and async/await driven by an event loop.
NPM Ecosystem: Node.js comes bundled with npm (Node Package Manager), the world's largest ecosystem of open-source libraries.

Web Browser vs Node.js

Feature	Browser Environment	Node.js Environment
Global Object	`window`	`global`
DOM Access	Available (`document`, `element`)	Unavailable
File System Access	Strictly Restricted (Security)	Full Access (`fs` module)
Module System	ES Modules (`import`/`export`)	CommonJS (`require`) & ES Modules

// hello.js
console.log("Hello from Node.js runtime!");
console.log("Current Process ID:", process.pid);
console.log("Node Version:", process.version);

TL;DR

Node.js is a server-side JavaScript runtime powered by Chrome's V8 engine.
It executes JavaScript outside browser boundaries with full operating system access.
Operates asynchronously with an event-driven architecture.