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Code playground

Monaco editor with separate Output and Stdin tabs. JavaScript, TypeScript, and Node-style snippets run in a sandboxed iframe with console capture (no package installs on our servers). Python and notebooks use Pyodide in the browser. Go compiles through the official Go Playground API. Use Ctrl+Enter to run ( Cmd on Mac).

Languages and runtimes

The playground groups modes behind tabs at the top: JavaScript and TypeScript execute transpiled code inside a dedicated sandbox iframe that forwards console.log output back to the parent page. Node.js reuses the same engine with a small compatibility layer so simple readline examples can read lines from the Stdin tab — it is still not a full Node install. Python and the Notebook mode load Pyodide on first use; subsequent runs reuse the interpreter. Go sends your main package to the official Go Playground API and prints compiler and program output in the Output tab.

Output and standard input

The right column switches between Output (stdout, stderr, or console capture) and Stdin. For Python, lines from Stdin are fed to sys.stdin in order; notebooks share one Stdin buffer across Run and Run all. This matches how developers test CLIs locally without juggling separate windows.

Keyboard shortcuts

Press Ctrl+Enter (or Cmd+Enter on macOS) to run the active editor or cell. The shortcut is scoped to the playground page so it does not steal focus from other inputs unintentionally.