sprockets-helpers

Asset path helpers for Sprockets 4.x & 3.x & <= 2.2 applications

Sprockets::Helpers adds the asset_path helpers, familiar to Rails developers, to Sprockets 2.x assets and applications.

Features

Includes helpers for image, javascript, stylesheet, font, video, & audio assets.
Automatically appends extension if necessary.
Optionally outputs digest paths.
Falls back to file paths in the public directory & adds cache busting timestamp.

Installation

$ gem install sprockets-helpers

Setup

Let's build a simple Sinatra app using Sprockets and Sprockets::Helpers (See my fork of sinatra-asset-pipeline for complete setup):

require 'sinatra/base'
require 'sprockets'
require 'sprockets-helpers'

class App < Sinatra::Base
  set :sprockets, Sprockets::Environment.new(root)
  set :assets_prefix, '/assets'
  set :digest_assets, false

  configure do
    # Setup Sprockets
    sprockets.append_path File.join(root, 'assets', 'stylesheets')
    sprockets.append_path File.join(root, 'assets', 'javascripts')
    sprockets.append_path File.join(root, 'assets', 'images')

    # Configure Sprockets::Helpers (if necessary)
    Sprockets::Helpers.configure do |config|
      config.environment = sprockets
      config.prefix      = assets_prefix
      config.digest      = digest_assets
      config.public_path = public_folder

      # Force to debug mode in development mode
      # Debug mode automatically sets
      # expand = true, digest = false, manifest = false
      config.debug       = true if development?
    end
  end

  helpers do
    include Sprockets::Helpers

    # Alternative method for telling Sprockets::Helpers which
    # Sprockets environment to use.
    # def assets_environment
    #   settings.sprockets
    # end
  end

  get '/' do
    erb :index
  end
end

Usage in Assets

Simply requiring sprockets-helpers will add the asset path helpers to the Sprocket context, making them available within any asset. For example, a file assets/javascripts/paths.js.erb:

var Paths = { railsImage: "<%= image_path 'rails.png' %>" };

Would be transformed into:

var Paths = { railsImage: '/assets/rails.png' };

Usage in the App

The helpers can also be used in the app itself. You just include the Sprockets::Helpers module and set Sprockets::Helpers.environment to the Sprockets environment to search for the assets. Alternatively you can define an #assets_environment method in the context of #asset_path, which returns a reference to the Sprockets environment (see above).

Now the following index file:

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Sinatra with Sprockets 2 (Asset Pipeline)</title>
    <link rel="stylesheet" href="<%= stylesheet_path 'application' %>">
    <script src="<%= javascript_path 'application' %>"></script>
  </head>
  <body>
    <img src="<%= image_path 'rails.png' %>">
  </body>
</html>

Would become:

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Sinatra with Sprockets 2 (Asset Pipeline)</title>
    <link rel="stylesheet" href="/assets/application.css">
    <script src="/assets/application.js"></script>
  </head>
  <body>
    <img src="/assets/rails.png">
  </body>
</html>

Even better, you can use #javascript_tag and #stylesheet_tag directly, which optionally handle the expansion of assets for debugging like Rails:

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Sinatra with Sprockets 2 (Asset Pipeline)</title>
    <%= stylesheet_tag 'application' %>
    <%= javascript_tag 'application', :expand => true %>
  </head>
  <body>
    <img src="<%= image_path 'rails.png' %>">
  </body>
</html>

Would become:

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Sinatra with Sprockets 2 (Asset Pipeline)</title>
    <link rel="stylesheet" href="/assets/application.css">
    <script src="/assets/jquery.js?body=1"></script>
    <script src="/assets/jquery.ui.js?body=1"></script>
    <script src="/assets/application.js?body=1"></script>
  </head>
  <body>
    <img src="/assets/rails.png">
  </body>
</html>

Fallback to Public Directory

If the source is not an asset in the Sprockets environment, Sprockets::Helpers will fallback to looking for the file in the application's public directory. It will also append the cache busting timestamp of the file. For example:

Given an image, public/images/logo.jpg:

<img src="<%= image_path 'logo.jpg' %>">

Would become:

<img src='/images/logo.jpg?1320093919'>

Manifest Usage

Sprockets::Helpers will use the latest fingerprinted filename directly from a manifest.json file:

# ...
Sprockets::Helpers.configure do |config|
  config.environment = sprockets
  config.manifest    = Sprockets::Manifest.new(sprockets, 'path/to/manifset.json')
  config.prefix      = assets_prefix
  config.public_path = public_folder
end
# ...

Sinatra Integration

New in 1.0: there is an easier way to integrate with Sinatra applications. You can register the Sinatra::Sprockets::Helpers extension and it will automatically include the helpers:

require 'sinatra/base'
require 'sprockets'
require 'sinatra/sprockets-helpers'

class App < Sinatra::Base
  register Sinatra::Sprockets::Helpers
  set :sprockets, Sprockets::Environment.new(root)
  set :assets_prefix, '/assets'
  set :digest_assets, true

  configure do
    # Setup Sprockets
    sprockets.append_path File.join(root, 'assets', 'stylesheets')
    sprockets.append_path File.join(root, 'assets', 'javascripts')
    sprockets.append_path File.join(root, 'assets', 'images')

    configure_sprockets_helpers do |helpers|
      # This will automatically configure Sprockets::Helpers based on the
      # `sprockets`, `public_folder`, `assets_prefix`, and `digest_assets`
      # settings if they exist. Otherwise you can configure as normal:
      helpers.asset_host = 'some-bucket.s3.amazon.com'
    end
  end

  get '/' do
    erb :index
  end
end

Roda Integration

See: https://github.com/hmdne/roda-sprockets