CoffeeScript · version 2

Run CoffeeScript 2 online

CoffeeScript 2 — run it in a Firecracker microVM on ls-judge. Real toolchain, no wrapper.

Starter code

What you get in CoffeeScript 2

Clicking "Run now" opens the playground with this exact code and a matching test case — passes on first Run.

coffeescript
CoffeeScript 2
lines = []
process.stdin.on 'data', (d) -> lines.push d.toString()
process.stdin.on 'end', ->
  n = parseInt lines.join('').trim()
  process.stdout.write "#{n*2}\n"
stdin →21
expected →42
How it runs

How ls-judge runs CoffeeScript 2

Every submission is compiled and executed inside its own Firecracker microVM — the same isolation primitive AWS Lambda uses. No shared container, no shared kernel with other users' code. The CoffeeScript 2toolchain shipped with the microVM is the real thing (not a browser-side emulation): syscalls behave the way they do in production, and the compile / runtime behaviour matches what you would see on your own machine with that version installed.

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