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diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md index fa4e714950..ff6787dae5 100644 --- a/guides/source/asset_pipeline.md +++ b/guides/source/asset_pipeline.md @@ -1,15 +1,15 @@ The Asset Pipeline ================== -This guide covers the asset pipeline introduced in Rails 3.1. +This guide covers the asset pipeline. After reading this guide, you will know: -* Understand what the asset pipeline is and what it does. -* Properly organize your application assets. -* Understand the benefits of the asset pipeline. -* Add a pre-processor to the pipeline. -* Package assets with a gem. +* How to understand what the asset pipeline is and what it does. +* How to properly organize your application assets. +* How to understand the benefits of the asset pipeline. +* How to add a pre-processor to the pipeline. +* How to package assets with a gem. -------------------------------------------------------------------------------- @@ -18,11 +18,9 @@ What is the Asset Pipeline? The asset pipeline provides a framework to concatenate and minify or compress JavaScript and CSS assets. It also adds the ability to write these assets in other languages such as CoffeeScript, Sass and ERB. -Prior to Rails 3.1 these features were added through third-party Ruby libraries such as Jammit and Sprockets. Rails 3.1 is integrated with Sprockets through Action Pack which depends on the `sprockets` gem, by default. - Making the asset pipeline a core feature of Rails means that all developers can benefit from the power of having their assets pre-processed, compressed and minified by one central library, Sprockets. This is part of Rails' "fast by default" strategy as outlined by DHH in his keynote at RailsConf 2011. -In Rails 3.1, the asset pipeline is enabled by default. It can be disabled in `config/application.rb` by putting this line inside the application class definition: +The asset pipeline is enabled by default. It can be disabled in `config/application.rb` by putting this line inside the application class definition: ```ruby config.assets.enabled = false @@ -100,7 +98,24 @@ In production, Rails precompiles these files to `public/assets` by default. The When you generate a scaffold or a controller, Rails also generates a JavaScript file (or CoffeeScript file if the `coffee-rails` gem is in the `Gemfile`) and a Cascading Style Sheet file (or SCSS file if `sass-rails` is in the `Gemfile`) for that controller. -For example, if you generate a `ProjectsController`, Rails will also add a new file at `app/assets/javascripts/projects.js.coffee` and another at `app/assets/stylesheets/projects.css.scss`. You should put any JavaScript or CSS unique to a controller inside their respective asset files, as these files can then be loaded just for these controllers with lines such as `<%= javascript_include_tag params[:controller] %>` or `<%= stylesheet_link_tag params[:controller] %>`. +For example, if you generate a `ProjectsController`, Rails will also add a new file at `app/assets/javascripts/projects.js.coffee` and another at `app/assets/stylesheets/projects.css.scss`. You should put any JavaScript or CSS unique to a controller inside their respective asset files, as these files can then be loaded just for these controllers with lines such as `<%= javascript_include_tag params[:controller] %>` or `<%= stylesheet_link_tag params[:controller] %>`. Note that you have to set `config.assets.precompile` in `config/environments/production.rb` if you want to precomepile them and use in production mode. You can append them one by one or do something like this: + + # config/environments/production.rb + config.assets.precompile << Proc.new { |path| + if path =~ /\.(css|js)\z/ + full_path = Rails.application.assets.resolve(path).to_path + app_assets_path = Rails.root.join('app', 'assets').to_path + if full_path.starts_with? app_assets_path + puts "including asset: " + full_path + true + else + puts "excluding asset: " + full_path + false + end + else + false + end + } NOTE: You must have an [ExecJS](https://github.com/sstephenson/execjs#readme) supported runtime in order to use CoffeeScript. If you are using Mac OS X or Windows you have a JavaScript runtime installed in your operating system. Check [ExecJS](https://github.com/sstephenson/execjs#readme) documentation to know all supported JavaScript runtimes. @@ -114,7 +129,7 @@ Pipeline assets can be placed inside an application in one of three locations: ` * `vendor/assets` is for assets that are owned by outside entities, such as code for JavaScript plugins and CSS frameworks. -#### Search paths +#### Search Paths When a file is referenced from a manifest or a helper, Sprockets searches the three default asset locations for it. @@ -162,7 +177,7 @@ Paths are traversed in the order that they occur in the search path. By default, It is important to note that files you want to reference outside a manifest must be added to the precompile array or they will not be available in the production environment. -#### Using index files +#### Using Index Files Sprockets uses files named `index` (with the relevant extensions) for a special purpose. @@ -270,8 +285,6 @@ For example, a new Rails application includes a default `app/assets/javascripts/ In JavaScript files, the directives begin with `//=`. In this case, the file is using the `require` and the `require_tree` directives. The `require` directive is used to tell Sprockets the files that you wish to require. Here, you are requiring the files `jquery.js` and `jquery_ujs.js` that are available somewhere in the search path for Sprockets. You need not supply the extensions explicitly. Sprockets assumes you are requiring a `.js` file when done from within a `.js` file. -NOTE. In Rails 3.1 the `jquery-rails` gem provides the `jquery.js` and `jquery_ujs.js` files via the asset pipeline. You won't see them in the application tree. - The `require_tree` directive tells Sprockets to recursively include _all_ JavaScript files in the specified directory into the output. These paths must be specified relative to the manifest file. You can also use the `require_directory` directive which includes all JavaScript files only in the directory specified, without recursion. Directives are processed top to bottom, but the order in which files are included by `require_tree` is unspecified. You should not rely on any particular order among those. If you need to ensure some particular JavaScript ends up above some other in the concatenated file, require the prerequisite file first in the manifest. Note that the family of `require` directives prevents files from being included twice in the output. @@ -337,7 +350,7 @@ would generate this HTML: The `body` param is required by Sprockets. -### Turning Debugging off +### Turning Debugging Off You can turn off debug mode by updating `config/environments/development.rb` to include: @@ -462,7 +475,7 @@ The default location for the manifest is the root of the location specified in ` NOTE: If there are missing precompiled files in production you will get an `Sprockets::Helpers::RailsHelper::AssetPaths::AssetNotPrecompiledError` exception indicating the name of the missing file(s). -#### Far-future Expires header +#### Far-future Expires Header Precompiled assets exist on the filesystem and are served directly by your web server. They do not have far-future headers by default, so to get the benefit of fingerprinting you'll have to update your server configuration to add them. @@ -492,7 +505,7 @@ location ~ ^/assets/ { } ``` -#### GZip compression +#### GZip Compression When files are precompiled, Sprockets also creates a [gzipped](http://en.wikipedia.org/wiki/Gzip) (.gz) version of your assets. Web servers are typically configured to use a moderate compression ratio as a compromise, but since precompilation happens once, Sprockets uses the maximum compression ratio, thus reducing the size of the data transfer to the minimum. On the other hand, web servers can be configured to serve compressed content directly from disk, rather than deflating non-compressed files themselves. @@ -648,7 +661,7 @@ This can be changed to something else: config.assets.prefix = "/some_other_path" ``` -This is a handy option if you are updating an existing project (pre Rails 3.1) that already uses this path or you wish to use this path for a new resource. +This is a handy option if you are updating an older project that didn't use the asset pipeline and that already uses this path or you wish to use this path for a new resource. ### X-Sendfile Headers |