JavaScript Practice

Nine short, hands-on JavaScript lessons: start with your first variable, build up through closures and classes, debug a real thrown error from its stack trace, then finish with a capstone kata that combines functions, arrays, and objects. Each lesson gives you a task and a Run button - your code is checked against real tests the moment you run it. Everything runs in your browser.

Start with lesson 1. You can leave and come back any time - your code is saved locally.