Hello, World!
console.log 'Hello, World!'main.coffee
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main.coffee · output appears here
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CoffeeScript 2.7.0Readymain.coffeeLn 1, Col 1Spaces: 4UTF-8
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main.coffee · output appears here
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Output streams here as your program runs.
CoffeeScript is a small programming language that compiles into JavaScript, created by Jeremy Ashkenas and first released in 2009. It offers a cleaner, more concise syntax inspired by Ruby and Python, removing curly braces and semicolons in favor of significant whitespace. Its motto is that it is 'just JavaScript,' so every CoffeeScript program maps directly to readable JavaScript output while adding conveniences like comprehensions and the existential operator.
On CompileBytes, CoffeeScript is processed with the compiler reported as version 2.5.1, which targets modern JavaScript. Although the language has declined in popularity since the rise of ES6 and TypeScript, it remains useful for learning, for legacy codebases, and for writing terse scripts. CoffeeScript code runs in Node.js after compilation, so it has full access to the JavaScript runtime and ecosystem.
main.coffee is the entry point for each run.
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console.log 'Hello, World!'square = (n) -> n * n
console.log square 5cubes = (x * x * x for x in [1..5])
console.log cubesperson =
name: 'Ada'
age: 36
for key, value of person
console.log "#{key}: #{value}"factorial = (n) ->
if n <= 1 then 1 else n * factorial n - 1
console.log factorial 6nums = [1..10]
evens = (n for n in nums when n % 2 is 0)
console.log evensclass Animal
constructor: (@name) ->
speak: -> "#{@name} makes a sound"
dog = new Animal 'Rex'
console.log dog.speak()[a, b, c] = [1, 2, 3]
console.log a + b + c
{name, age} = {name: 'Tom', age: 42}
console.log "#{name} is #{age}"grade = (n) ->
switch
when n >= 90 then 'A'
when n >= 80 then 'B'
else 'C'
console.log grade 85The editor uses Monaco, the engine behind VS Code, with language-aware editing tools and familiar keyboard controls.
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CoffeeScript is one of 46 single-file compiler scratchpads. Each run submits only main.coffee; local sibling-file imports are not enabled.
Linked-project languages (23): Node.js, TypeScript, Deno, Python, C, Go, Dart, Swift, Rust, Ruby, PHP, Java, Kotlin, C++, C#, Nim, Crystal, Haxe, Zig, Scala, D, Bun, Objective-C.
Single-file scratchpads (46): Matplotlib, NumPy, pandas, Haskell, Clojure, Perl, Lua, Tcl, jq, Raku, Elixir, Bash, Zsh, Nushell, R, Assembly (NASM), Julia, Octave, Groovy, PowerShell, Visual Basic .NET, Odin, Pascal, Lisp, Erlang, CoffeeScript, COBOL, BASIC, V, Racket, OCaml, Prolog, AWK, Emacs Lisp, Emojicode, Forth, F#, Fortran, Assembly (NASM64), Solidity, Mojo, Ada, WASM (WAT), Gleam, Shell Script (sh), Scheme.
Download file exports the active CoffeeScript source file.