Introduction to JavaScript

What is JavaScript?

JavaScript is a lightweight, interpreted programming language with first-class functions. It is most well-known as the scripting language for Web pages, but it is also used in many non-browser environments such as Node.js.

Where does JavaScript run?

• Browser — Chrome, Firefox, Safari, Edge all have built-in JS engines
• Server — Node.js allows running JS on the backend
• Mobile — React Native, Ionic
• Desktop — Electron (VS Code is built with it!)

Your first JavaScript program

console.log("Hello, World!");

Run this in your browser console (F12 → Console) or in the online compiler above.

Why learn JavaScript?

• 🌐 The only language that runs natively in browsers
• 📈 #1 most used language on GitHub for 10+ years
• 💼 High demand — millions of job openings worldwide
• 🚀 Full-stack — frontend AND backend with Node.js