Module | ActionView::Helpers::AssetTagHelper
In: | lib/action_view/helpers/asset_tag_helper.rb

Provides methods for linking an HTML page together with other assets such as images, javascripts, stylesheets, and feeds. You can direct Rails to link to assets from a dedicated assets server by setting ActionController::Base.asset_host in your environment.rb. These methods do not verify the assets exist before linking to them.

      ActionController::Base.asset_host = "http://assets.example.com"
      image_tag("rails.png")
        => <img src="http://assets.example.com/images/rails.png" alt="Rails" />
      stylesheet_include_tag("application")
        => <link href="http://assets.example.com/stylesheets/application.css" media="screen" rel="Stylesheet" type="text/css" />

### Methods

auto_discovery_link_tag image_path image_tag javascript_include_tag javascript_path register_javascript_include_default stylesheet_link_tag stylesheet_path

### Constants

JAVASCRIPT_DEFAULT_SOURCES | = | ['prototype', 'effects', 'dragdrop', 'controls'] unless const_defined?(:JAVASCRIPT_DEFAULT_SOURCES)

### Public Class methods

register_javascript_include_default(*sources)

Register one or more additional JavaScript files to be included when `javascript_include_tag :defaults` is called. This method is only intended to be called from plugin initialization to register additional .js files that the plugin installed in `public/javascripts`.

### Public Instance methods

auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})

Returns a link tag that browsers and news readers can use to auto-detect an RSS or ATOM feed. The `type` can either be `:rss` (default) or `:atom`. Control the link options in url_for format using the `url_options`. You can modify the LINK tag itself in `tag_options`.

Tag Options:

- `:rel` - Specify the relation of this link, defaults to "alternate"
- `:type` - Override the auto-generated mime type
- `:title` - Specify the title of the link, defaults to the `type`

     auto_discovery_link_tag # =>
        <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.curenthost.com/controller/action" />
     auto_discovery_link_tag(:atom) # =>
        <link rel="alternate" type="application/atom+xml" title="ATOM" href="http://www.curenthost.com/controller/action" />
     auto_discovery_link_tag(:rss, {:action => "feed"}) # =>
        <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.curenthost.com/controller/feed" />
     auto_discovery_link_tag(:rss, {:action => "feed"}, {:title => "My RSS"}) # =>
        <link rel="alternate" type="application/rss+xml" title="My RSS" href="http://www.curenthost.com/controller/feed" />

image_path(source)

Computes the path to an image asset in the public images directory. Full paths from the document root will be passed through. Used internally by image_tag to build the image path. Passing a filename without an extension is deprecated.

      image_path("edit.png")  # => /images/edit.png
      image_path("icons/edit.png")  # => /images/icons/edit.png
      image_path("/icons/edit.png")  # => /icons/edit.png

image_tag(source, options = {})

Returns an html image tag for the `source`. The `source` can be a full path or a file that exists in your public images directory. Note that specifying a filename without the extension is now deprecated in Rails. You can add html attributes using the `options`. The `options` supports two additional keys for convienence and conformance:

- `:alt` - If no alt text is given, the file name part of the `source` is used (capitalized and without the extension)
- `:size` - Supplied as "{Width}x{Height}", so "30x45" becomes width="30" and height="45". `:size` will be ignored if the value is not in the correct format.

     image_tag("icon.png")  # =>
       <img src="/images/icon.png" alt="Icon" />
     image_tag("icon.png", :size => "16x10", :alt => "Edit Entry")  # =>
       <img src="/images/icon.png" width="16" height="10" alt="Edit Entry" />
     image_tag("/icons/icon.gif", :size => "16x16")  # =>
       <img src="/icons/icon.gif" width="16" height="16" alt="Icon" />

javascript_include_tag(*sources)

Returns an html script tag for each of the `sources` provided. You can pass in the filename (.js extension is optional) of javascript files that exist in your public/javascripts directory for inclusion into the current page or you can pass the full path relative to your document root. To include the Prototype and Scriptaculous javascript libraries in your application, pass `:defaults` as the source. When using :defaults, if an `application.js` file exists in your public javascripts directory, it will be included as well. You can modify the html attributes of the script tag by passing a hash as the last argument.

      javascript_include_tag "xmlhr" # =>
        <script type="text/javascript" src="/javascripts/xmlhr.js"></script>

      javascript_include_tag "common.javascript", "/elsewhere/cools" # =>
        <script type="text/javascript" src="/javascripts/common.javascript"></script>
        <script type="text/javascript" src="/elsewhere/cools.js"></script>

      javascript_include_tag :defaults # =>
        <script type="text/javascript" src="/javascripts/prototype.js"></script>
        <script type="text/javascript" src="/javascripts/effects.js"></script>
        ...
        <script type="text/javascript" src="/javascripts/application.js"></script> *see below

javascript_path(source)

Computes the path to a javascript asset in the public javascripts directory. If the `source` filename has no extension, .js will be appended. Full paths from the document root will be passed through. Used internally by javascript_include_tag to build the script path.

      javascript_path "xmlhr" # => /javascripts/xmlhr.js
      javascript_path "dir/xmlhr.js" # => /javascripts/dir/xmlhr.js
      javascript_path "/dir/xmlhr" # => /dir/xmlhr.js

stylesheet_link_tag(*sources)

Returns a stylesheet link tag for the sources specified as arguments. If you don‘t specify an extension, .css will be appended automatically. You can modify the link attributes by passing a hash as the last argument.

      stylesheet_link_tag "style" # =>
        <link href="/stylesheets/style.css" media="screen" rel="Stylesheet" type="text/css" />

      stylesheet_link_tag "style", :media => "all" # =>
        <link href="/stylesheets/style.css" media="all" rel="Stylesheet" type="text/css" />

      stylesheet_link_tag "random.styles", "/css/stylish" # =>
        <link href="/stylesheets/random.styles" media="screen" rel="Stylesheet" type="text/css" />
        <link href="/css/stylish.css" media="screen" rel="Stylesheet" type="text/css" />

stylesheet_path(source)

Computes the path to a stylesheet asset in the public stylesheets directory. If the `source` filename has no extension, .css will be appended. Full paths from the document root will be passed through. Used internally by stylesheet_link_tag to build the stylesheet path.

      stylesheet_path "style" # => /stylesheets/style.css
      stylesheet_path "dir/style.css" # => /stylesheets/dir/style.css
      stylesheet_path "/dir/style.css" # => /dir/style.css

[Validate]