You Don't Know JS Yet
The 2nd-edition rewrite of Kyle Simpson's deep dive into JavaScript: scope and closures, the `this` binding rules, type coercion semantics, sync/async patterns, and the language's modern features. CC BY-NC-ND 4.0 — exercises lift Simpson's example code (MIT) and let learners drill the load-bearing primitives.
- JavaScript
- 25 lessons
- ~5 hours
- Free
- by Kyle Simpson
Learn JavaScript for free on Libre Academy with the You Don't Know JS Yet course: 25 interactive lessons you complete by writing real code in a built-in editor, graded instantly by hidden tests. No paywall, no sign-up — it runs in your browser and the free desktop app.
What you get
- Hands-on lessons with a real editor and instant, test-graded feedback.
- Free and open source — no account required to start.
- Runs in your browser, and offline in the free desktop app.
- JavaScript runs in your browser.
What's inside
- Getting Started
- Scope & Closures
- Objects & Prototypes
- Types & Grammar
- Sync & Async
- ES.Next & Beyond
Start You Don't Know JS Yet free → More free JavaScript courses