module ActionView::Helpers::AssetTagHelper

This module provides methods for generating HTML that links views to assets such as images, JavaScripts, stylesheets, and feeds. These methods do not verify the assets exist before linking to them:

image_tag("rails.png")
# => <img alt="Rails" src="/assets/rails.png" />
stylesheet_link_tag("application")
# => <link href="/assets/application.css?body=1" media="screen" rel="stylesheet" />

Public Instance Methods

audio_tag(*sources) click to toggle source

Returns an HTML audio tag for the source. The source can be full path or file that exists in your public audios directory.

audio_tag("sound")
# => <audio src="/audios/sound"></audio>
audio_tag("sound.wav")
# => <audio src="/audios/sound.wav"></audio>
audio_tag("sound.wav", autoplay: true, controls: true)
# => <audio autoplay="autoplay" controls="controls" src="/audios/sound.wav"></audio>
audio_tag("sound.wav", "sound.mid")
# => <audio><source src="/audios/sound.wav" /><source src="/audios/sound.mid" /></audio>
# File lib/action_view/helpers/asset_tag_helper.rb, line 327
def audio_tag(*sources)
  multiple_sources_tag_builder("audio", sources)
end
image_alt(src) click to toggle source

Returns a string suitable for an HTML image tag alt attribute. The src argument is meant to be an image file path. The method removes the basename of the file path and the digest, if any. It also removes hyphens and underscores from file names and replaces them with spaces, returning a space-separated, titleized string.

Examples

image_alt('rails.png')
# => Rails

image_alt('hyphenated-file-name.png')
# => Hyphenated file name

image_alt('underscored_file_name.png')
# => Underscored file name
# File lib/action_view/helpers/asset_tag_helper.rb, line 259
def image_alt(src)
  File.basename(src, ".*".freeze).sub(/-[[:xdigit:]]{32,64}\z/, "".freeze).tr("-_".freeze, " ".freeze).capitalize
end
image_tag(source, options = {}) click to toggle source

Returns an HTML image tag for the source. The source can be a full path or a file.

Options

You can add HTML attributes using the options. The options supports two additional keys for convenience 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}” or “{Number}”, so “30x45” becomes width=“30” and height=“45”, and “50” becomes width=“50” and height=“50”. :size will be ignored if the value is not in the correct format.

Examples

image_tag("icon")
# => <img alt="Icon" src="/assets/icon" />
image_tag("icon.png")
# => <img alt="Icon" src="/assets/icon.png" />
image_tag("icon.png", size: "16x10", alt: "Edit Entry")
# => <img src="/assets/icon.png" width="16" height="10" alt="Edit Entry" />
image_tag("/icons/icon.gif", size: "16")
# => <img src="/icons/icon.gif" width="16" height="16" alt="Icon" />
image_tag("/icons/icon.gif", height: '32', width: '32')
# => <img alt="Icon" height="32" src="/icons/icon.gif" width="32" />
image_tag("/icons/icon.gif", class: "menu_icon")
# => <img alt="Icon" class="menu_icon" src="/icons/icon.gif" />
image_tag("/icons/icon.gif", data: { title: 'Rails Application' })
# => <img data-title="Rails Application" src="/icons/icon.gif" />
# File lib/action_view/helpers/asset_tag_helper.rb, line 228
def image_tag(source, options = {})
  options = options.symbolize_keys
  check_for_image_tag_errors(options)

  src = options[:src] = path_to_image(source, skip_pipeline: options.delete(:skip_pipeline))

  unless src.start_with?("cid:") || src.start_with?("data:") || src.blank?
    options[:alt] = options.fetch(:alt) { image_alt(src) }
  end

  options[:width], options[:height] = extract_dimensions(options.delete(:size)) if options[:size]
  tag("img", options)
end
javascript_include_tag(*sources) click to toggle source

Returns an HTML script tag for each of the sources provided.

Sources may be paths to JavaScript files. Relative paths are assumed to be relative to assets/javascripts, full paths are assumed to be relative to the document root. Relative paths are idiomatic, use absolute paths only when needed.

When passing paths, the “.js” extension is optional. If you do not want “.js” appended to the path extname: false can be set on the options.

You can modify the HTML attributes of the script tag by passing a hash as the last argument.

When the Asset Pipeline is enabled, you can pass the name of your manifest as source, and include other JavaScript or CoffeeScript files inside the manifest.

Options

When the last parameter is a hash you can add HTML attributes using that parameter. The following options are supported:

  • :extname - Append an extension to the generated url unless the extension already exists. This only applies for relative urls.

  • :protocol - Sets the protocol of the generated url, this option only applies when a relative url and host options are provided.

  • :host - When a relative url is provided the host is added to the that path.

  • :skip_pipeline - This option is used to bypass the asset pipeline when it is set to true.

Examples

javascript_include_tag "xmlhr"
# => <script src="/assets/xmlhr.debug-1284139606.js"></script>

javascript_include_tag "xmlhr", host: "localhost", protocol: "https"
# => <script src="https://localhost/assets/xmlhr.debug-1284139606.js"></script>

javascript_include_tag "template.jst", extname: false
# => <script src="/assets/template.debug-1284139606.jst"></script>

javascript_include_tag "xmlhr.js"
# => <script src="/assets/xmlhr.debug-1284139606.js"></script>

javascript_include_tag "common.javascript", "/elsewhere/cools"
# => <script src="/assets/common.javascript.debug-1284139606.js"></script>
#    <script src="/elsewhere/cools.debug-1284139606.js"></script>

javascript_include_tag "http://www.example.com/xmlhr"
# => <script src="http://www.example.com/xmlhr"></script>

javascript_include_tag "http://www.example.com/xmlhr.js"
# => <script src="http://www.example.com/xmlhr.js"></script>
# File lib/action_view/helpers/asset_tag_helper.rb, line 75
def javascript_include_tag(*sources)
  options = sources.extract_options!.stringify_keys
  path_options = options.extract!("protocol", "extname", "host", "skip_pipeline").symbolize_keys
  sources.uniq.map { |source|
    tag_options = {
      "src" => path_to_javascript(source, path_options)
    }.merge!(options)
    content_tag("script".freeze, "", tag_options)
  }.join("\n").html_safe
end
video_tag(*sources) click to toggle source

Returns an HTML video tag for the sources. If sources is a string, a single video tag will be returned. If sources is an array, a video tag with nested source tags for each source will be returned. The sources can be full paths or files that exists in your public videos directory.

Options

You can add HTML attributes using the options. The options supports two additional keys for convenience and conformance:

  • :poster - Set an image (like a screenshot) to be shown before the video loads. The path is calculated like the src of image_tag.

  • :size - Supplied as “{Width}x{Height}” or “{Number}”, so “30x45” becomes width=“30” and height=“45”, and “50” becomes width=“50” and height=“50”. :size will be ignored if the value is not in the correct format.

  • :poster_skip_pipeline will bypass the asset pipeline when using the :poster option instead using an asset in the public folder.

Examples

video_tag("trailer")
# => <video src="/videos/trailer"></video>
video_tag("trailer.ogg")
# => <video src="/videos/trailer.ogg"></video>
video_tag("trailer.ogg", controls: true, preload: 'none')
# => <video preload="none" controls="controls" src="/videos/trailer.ogg" ></video>
video_tag("trailer.m4v", size: "16x10", poster: "screenshot.png")
# => <video src="/videos/trailer.m4v" width="16" height="10" poster="/assets/screenshot.png"></video>
video_tag("trailer.m4v", size: "16x10", poster: "screenshot.png", poster_skip_pipeline: true)
# => <video src="/videos/trailer.m4v" width="16" height="10" poster="screenshot.png"></video>
video_tag("/trailers/hd.avi", size: "16x16")
# => <video src="/trailers/hd.avi" width="16" height="16"></video>
video_tag("/trailers/hd.avi", size: "16")
# => <video height="16" src="/trailers/hd.avi" width="16"></video>
video_tag("/trailers/hd.avi", height: '32', width: '32')
# => <video height="32" src="/trailers/hd.avi" width="32"></video>
video_tag("trailer.ogg", "trailer.flv")
# => <video><source src="/videos/trailer.ogg" /><source src="/videos/trailer.flv" /></video>
video_tag(["trailer.ogg", "trailer.flv"])
# => <video><source src="/videos/trailer.ogg" /><source src="/videos/trailer.flv" /></video>
video_tag(["trailer.ogg", "trailer.flv"], size: "160x120")
# => <video height="120" width="160"><source src="/videos/trailer.ogg" /><source src="/videos/trailer.flv" /></video>
# File lib/action_view/helpers/asset_tag_helper.rb, line 305
def video_tag(*sources)
  options = sources.extract_options!.symbolize_keys
  public_poster_folder = options.delete(:poster_skip_pipeline)
  sources << options
  multiple_sources_tag_builder("video", sources) do |tag_options|
    tag_options[:poster] = path_to_image(tag_options[:poster], skip_pipeline: public_poster_folder) if tag_options[:poster]
    tag_options[:width], tag_options[:height] = extract_dimensions(tag_options.delete(:size)) if tag_options[:size]
  end
end

Private Instance Methods

check_for_image_tag_errors(options) click to toggle source
# File lib/action_view/helpers/asset_tag_helper.rb, line 358
def check_for_image_tag_errors(options)
  if options[:size] && (options[:height] || options[:width])
    raise ArgumentError, "Cannot pass a :size option with a :height or :width option"
  end
end
extract_dimensions(size) click to toggle source
# File lib/action_view/helpers/asset_tag_helper.rb, line 349
def extract_dimensions(size)
  size = size.to_s
  if /\A\d+x\d+\z/.match?(size)
    size.split("x")
  elsif /\A\d+\z/.match?(size)
    [size, size]
  end
end
multiple_sources_tag_builder(type, sources) { |options| ... } click to toggle source
# File lib/action_view/helpers/asset_tag_helper.rb, line 332
def multiple_sources_tag_builder(type, sources)
  options       = sources.extract_options!.symbolize_keys
  skip_pipeline = options.delete(:skip_pipeline)
  sources.flatten!

  yield options if block_given?

  if sources.size > 1
    content_tag(type, options) do
      safe_join sources.map { |source| tag("source", src: send("path_to_#{type}", source, skip_pipeline: skip_pipeline)) }
    end
  else
    options[:src] = send("path_to_#{type}", sources.first, skip_pipeline: skip_pipeline)
    content_tag(type, nil, options)
  end
end