meteor/meteor

---
title: coffeescript
description: Documentation of Meteor's `coffeescript` package.
---

[CoffeeScript](http://coffeescript.org/) is a little language that
compiles into JavaScript. It provides a simple syntax without lots of
braces and parentheses.  The code compiles one-to-one into the
equivalent JS, and there is no interpretation at runtime.

CoffeeScript is supported on both the client and the server. Files
ending with `.coffee`, `.litcoffee`, or `.coffee.md` are automatically
compiled to JavaScript.

### Namespacing and CoffeeScript

Here's how CoffeeScript works with Meteor's namespacing.

* Per the usual CoffeeScript convention, CoffeeScript variables are
  file-scoped by default (visible only in the `.coffee` file where
  they are defined.)

* When writing a package, CoffeeScript-defined variables can be
  exported like any other variable (see [Package.js](/api/packagejs.html)). Exporting a variable pulls it up to
  package scope, meaning that it will be visible to all of the code in
  your app or package (both `.js` and `.coffee` files).

* Package-scope variables declared in `.js` files are visible in any
  `.coffee` files in the same app or project.

* There is no way to make a package-scope variable from a `.coffee`
  file other than exporting it. We couldn't figure out a way to make
  this fit naturally inside the CoffeeScript language. If you want to
  use package-scope variables with CoffeeScript, one way is to make a
  short `.js` file that declares all of your package-scope
  variables. They can then be used and assigned to from `.coffee`
  files.

* If you want to share variables between `.coffee` files in the same
  package, and don't want to separately declare them in a `.js` file,
  we have an experimental feature that you may like. An object called
  `share` is visible in CoffeeScript code and is shared across all
  `.coffee` files in the same package. So, you can write `share.foo`
  for a value that is shared between all CoffeeScript code in a
  package, but doesn't escape that package.

Heavy CoffeeScript users, please let us know how this arrangement
works for you, whether `share` is helpful for you, and anything else
you'd like to see changed.

### Modules and CoffeeScript

See [Modules » Syntax » CoffeeScript](/packages/modules.html#CoffeeScript).