Lesson 1 / 40
What is JavaScript?
Learn what JavaScript is, where it runs from browsers to servers, and how it adds behaviour to HTML and CSS.
A language for the web
JavaScript is a high-level, dynamically-typed scripting language created by Brendan Eich in 1995. It's the only language browsers run natively.
Where JS runs
Originally browser-only, JS now runs on servers (Node.js), mobile apps (React Native), and even desktop apps (Electron).
JS vs HTML/CSS
If HTML is a page's skeleton and CSS its appearance, JavaScript is the behavior — it makes the page react and change.