beginner15 min
Introduction to JavaScript
What is JavaScript, where it runs, and your first script
Welcome to JavaScript
JavaScript is the programming language of the web. Every modern website uses it to create interactive experiences — from animated buttons to full web applications. It runs in every browser without installing anything.
Why Learn JavaScript?
- It's everywhere — frontend, backend (Node.js), mobile apps, even desktop apps
- Instant feedback — write code, refresh your browser, see results immediately
- Huge ecosystem — the largest package registry in the world (npm)
- High demand — consistently one of the most sought-after skills by employers
Your First JavaScript
Open your browser's console (F12 → Console) and type:
Output
Run your code to see output here
How JavaScript Runs
Unlike Python (which you may know from our other course), JavaScript runs directly in your browser. When you visit a webpage:
- The browser downloads the HTML, CSS, and JavaScript files
- The JavaScript engine (V8 in Chrome, SpiderMonkey in Firefox) executes the code
- The code can modify the page in real-time — changing text, colors, responding to clicks
Check Your Understanding
Where does JavaScript code execute?
Key Concepts Preview
In the next lessons, we'll cover:
- Variables — storing and working with data
- Functions — reusable blocks of code
- The DOM — making web pages interactive
Get ready to make things happen in the browser!