Lesson 1.1 — What is JavaScript
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Theory: The Behavior Layer
A web page is built from three layers, and JavaScript is the one that brings it to life:
- HTML — the structure and content
- CSS — the look and style
- JavaScript — the behavior and interactivity
With JavaScript you can respond to clicks, update the page without reloading, do calculations, and talk to servers.
Tab indents. Press Escape, then Tab, to leave the editor. Control or Command plus Enter runs the code.
Console
Press Run to see what your code prints.