Closure Sprockets

Sprockets preprocessor for Google's Closure tools + Closure-templates (soy) compiler + Closure stylesheets (gss) compiler.

Integrating with Rails 3

If you want to use closure as your Javascript library in Rails 3, add this gem to your Gemfile:

gem 'closure-sprockets'

The gem ships with a Railtie which will automatically register a Closure preprocessor. From here, three more steps:

Download the latest version of closure library from Google and put it in vendor/assets or another appropriate folder
Create require_file.js that will be your closure start point and include it with new directive require_closure at your application.js:
//= require_closure require_file
Write some closure code!

Javascripts

// in your javascript `require_file.js` file or any depended file
goog.require('goog.dom');

function sayHello() {
  newHeader = goog.dom.createDom('h1', {}, 'Hello world!');
  goog.dom.appendChild(document.body, newHeader);
};

window.onload = sayHello;

You can also add a name.soy template in your assets folder and require it by standard require directive, and it will be automatically compiled to Javascript for you! Ex:

/** hello.soy */

{namespace examples.simple}

/**
 * Says hello to the world.
 */
{template .helloSoy}
  Hello from Soy!
{/template}

//= require examples/simple

var soy = goog.dom.createDom('h1', {'style': 'background-color:#EEE'}, examples.simple.helloSoy());
goog.dom.appendChild(document.body, soy);

That's it! Point your browser at your page and you should have a hello world greeting from Google Closure, preprocessed by the Rails 3 Asset Pipeline and without any external Python dependencies or dynamic Javascript loading.

Stylesheets

You can use also closure stylesheets in .gss files

/** style.gss **/

@def BG_COLOR              rgb(235, 239, 249);

@def DIALOG_BORDER_COLOR   rgb(107, 144, 218);
@def DIALOG_BG_COLOR       BG_COLOR;

body {
  background-color: BG_COLOR;
}

.dialog {
  background-color: DIALOG_BG_COLOR;
  border: 1px solid DIALOG_BORDER_COLOR;
}

GSS files will be compiled automatically to CSS:

body {
  background-color: #ebeff9;
}
.dialog {
  background-color: #ebeff9;
  border: 1px solid #6b90da;
}

Using Closure Compressor for Minification

Closure also provides its own Javascript compressor. If you wish to use it, pull in the closure-compiler gem:

# in your Gemfile
gem 'closure-compiler'

# in your environment configuration
config.assets.js_compressor = Closure::Compiler.new

If you are not using the closure compiler, then you may want to disable the dynamic deps.js loading. To do so, add the following snippet in application.html.erb above the javascript_include tag:

<script type="text/javascript">
  var CLOSURE_NO_DEPS = true;
</script>