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Ruby CoffeeScript Compiler
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Ruby CoffeeScript

Ruby CoffeeScript is a bridge to the official CoffeeScript compiler.



gem install coffee-script

Note: This compiler library has replaced the original CoffeeScript compiler that was written in Ruby.


This library depends on the coffee-script-source gem which is updated any time a new version of CoffeeScript is released. (The coffee-script-source gem's version number is synced with each official CoffeeScript release.) This way you can build against different versions of CoffeeScript by requiring the correct version of the coffee-script-source gem.

In addition, you can use this library with unreleased versions of CoffeeScript by setting the COFFEESCRIPT_SOURCE_PATH environment variable:

export COFFEESCRIPT_SOURCE_PATH=/path/to/coffee-script/extras/coffee-script.js

The json library is also required but is not explicitly stated as a gem dependency. If you're on Ruby 1.8 you'll need to install the json or json_pure gem. On Ruby 1.9, json is included in the standard library.


The coffee-script library will automatically choose the best JavaScript engine for your platform. The currently implemented engines are:

  • Node.js. If the node binary is available in $PATH, it will be used to invoke the CoffeeScript compiler.

  • JavaScript Core. If you're on OS X and don't have Node.js installed, the library will fall back to the built-in JavaScript Core binary, jsc. This way you don't need to install any additional dependencies.

  • V8. Shelling out to Node.js may be too slow for your production environment. In this case, install therubyracer gem, which provides a fast bridge between Ruby and V8.

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