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Playground

The Playground

Write and run code in your browser. JavaScript and Python both work without any install. Your code is saved locally — close the tab and it'll still be here when you come back.

Output

Tips

Ctrl+Enter (or Cmd+Enter) runs the code.
Switching languages saves your current code first — switch back any time.
Python: the first run downloads ~10MB of Python runtime. Subsequent runs are instant.
JavaScript runs in a sandboxed function. alert() won't work; use console.log().
HTML mode renders the document live in an iframe.

What to Try

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Loop Examples

Try the loop patterns from the lesson.

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Function Exercises

Practice writing and calling functions.

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All Exercises

30+ small problems to work through.