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

Methods

Included Modules

Instance Public methods

audio_tag(*sources)

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

When the last parameter is a hash you can add HTML attributes using that parameter.

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>
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 458
      def audio_tag(*sources)
        multiple_sources_tag_builder("audio", sources)
      end
πŸ”Ž See on GitHub

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

  • :rel - Specify the relation of this link, defaults to β€œalternate”

  • :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.currenthost.com/controller/action" />
auto_discovery_link_tag(:atom)
# => <link rel="alternate" type="application/atom+xml" title="ATOM" href="http://www.currenthost.com/controller/action" />
auto_discovery_link_tag(:json)
# => <link rel="alternate" type="application/json" title="JSON" href="http://www.currenthost.com/controller/action" />
auto_discovery_link_tag(:rss, {action: "feed"})
# => <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.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.currenthost.com/controller/feed" />
auto_discovery_link_tag(:rss, {controller: "news", action: "feed"})
# => <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/news/feed" />
auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", {title: "Example RSS"})
# => <link rel="alternate" type="application/rss+xml" title="Example RSS" href="http://www.example.com/feed.rss" />
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 212
      def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
        if !(type == :rss || type == :atom || type == :json) && tag_options[:type].blank?
          raise ArgumentError.new("You should pass :type tag_option key explicitly, because you have passed #{type} type other than :rss, :atom, or :json.")
        end

        tag(
          "link",
          "rel"   => tag_options[:rel] || "alternate",
          "type"  => tag_options[:type] || Template::Types[type].to_s,
          "title" => tag_options[:title] || type.to_s.upcase,
          "href"  => url_options.is_a?(Hash) ? url_for(url_options.merge(only_path: false)) : url_options
        )
      end
πŸ”Ž See on GitHub

Returns a link tag for a favicon managed by the asset pipeline.

If a page has no link like the one generated by this helper, browsers ask for /favicon.ico automatically, and cache the file if the request succeeds. If the favicon changes it is hard to get it updated.

To have better control applications may let the asset pipeline manage their favicon storing the file under app/assets/images, and using this helper to generate its corresponding link tag.

The helper gets the name of the favicon file as first argument, which defaults to β€œfavicon.ico”, and also supports :rel and :type options to override their defaults, β€œshortcut icon” and β€œimage/x-icon” respectively:

favicon_link_tag
# => <link href="/assets/favicon.ico" rel="shortcut icon" type="image/x-icon" />

favicon_link_tag 'myicon.ico'
# => <link href="/assets/myicon.ico" rel="shortcut icon" type="image/x-icon" />

Mobile Safari looks for a different link tag, pointing to an image that will be used if you add the page to the home screen of an iOS device. The following call would generate such a tag:

favicon_link_tag 'mb-icon.png', rel: 'apple-touch-icon', type: 'image/png'
# => <link href="/assets/mb-icon.png" rel="apple-touch-icon" type="image/png" />
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 253
      def favicon_link_tag(source = "favicon.ico", options = {})
        tag("link", {
          rel: "shortcut icon",
          type: "image/x-icon",
          href: path_to_image(source, skip_pipeline: options.delete(:skip_pipeline))
        }.merge!(options.symbolize_keys))
      end
πŸ”Ž See on GitHub

image_tag(source, options = {})

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

Options

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

  • :size - Supplied as β€œ{Width}x{Height}” or β€œ{Number}”, so β€œ30x45” becomes width=β€œ30” and height=β€œ45”, and β€œ50” becomes width=β€œ50” and height=β€œ50”. :size will be ignored if the value is not in the correct format.

  • :srcset - If supplied as a hash or array of [source, descriptor] pairs, each image path will be expanded before the list is formatted as a string.

Examples

Assets (images that are part of your app):

image_tag("icon")
# => <img src="/assets/icon" />
image_tag("icon.png")
# => <img 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" />
image_tag("/icons/icon.gif", height: '32', width: '32')
# => <img height="32" src="/icons/icon.gif" width="32" />
image_tag("/icons/icon.gif", class: "menu_icon")
# => <img 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" />
image_tag("icon.png", srcset: { "icon_2x.png" => "2x", "icon_4x.png" => "4x" })
# => <img src="/assets/icon.png" srcset="/assets/icon_2x.png 2x, /assets/icon_4x.png 4x">
image_tag("pic.jpg", srcset: [["pic_1024.jpg", "1024w"], ["pic_1980.jpg", "1980w"]], sizes: "100vw")
# => <img src="/assets/pic.jpg" srcset="/assets/pic_1024.jpg 1024w, /assets/pic_1980.jpg 1980w" sizes="100vw">

Active Storage blobs (images that are uploaded by the users of your app):

image_tag(user.avatar)
# => <img src="/rails/active_storage/blobs/.../tiger.jpg" />
image_tag(user.avatar.variant(resize_to_limit: [100, 100]))
# => <img src="/rails/active_storage/representations/.../tiger.jpg" />
image_tag(user.avatar.variant(resize_to_limit: [100, 100]), size: '100')
# => <img width="100" height="100" src="/rails/active_storage/representations/.../tiger.jpg" />
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 370
      def image_tag(source, options = {})
        options = options.symbolize_keys
        check_for_image_tag_errors(options)
        skip_pipeline = options.delete(:skip_pipeline)

        options[:src] = resolve_image_source(source, skip_pipeline)

        if options[:srcset] && !options[:srcset].is_a?(String)
          options[:srcset] = options[:srcset].map do |src_path, size|
            src_path = path_to_image(src_path, skip_pipeline: skip_pipeline)
            "#{src_path} #{size}"
          end.join(", ")
        end

        options[:width], options[:height] = extract_dimensions(options.delete(:size)) if options[:size]
        tag("img", options)
      end
πŸ”Ž See on GitHub

javascript_include_tag(*sources)

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 β€œ.js” extension is optional. If you do not want β€œ.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.

If the server supports Early Hints header links for these assets will be automatically pushed.

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.

  • :nonce - When set to true, adds an automatic nonce value if you have Content Security Policy enabled.

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>

javascript_include_tag "http://www.example.com/xmlhr.js", nonce: true
# => <script src="http://www.example.com/xmlhr.js" nonce="..."></script>
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 88
      def javascript_include_tag(*sources)
        options = sources.extract_options!.stringify_keys
        path_options = options.extract!("protocol", "extname", "host", "skip_pipeline").symbolize_keys
        preload_links = []
        nopush = options["nopush"].nil? ? true : options.delete("nopush")
        crossorigin = options.delete("crossorigin")
        crossorigin = "anonymous" if crossorigin == true
        integrity = options["integrity"]

        sources_tags = sources.uniq.map { |source|
          href = path_to_javascript(source, path_options)
          if preload_links_header && !options["defer"]
            preload_link = "<#{href}>; rel=preload; as=script"
            preload_link += "; crossorigin=#{crossorigin}" unless crossorigin.nil?
            preload_link += "; integrity=#{integrity}" unless integrity.nil?
            preload_link += "; nopush" if nopush
            preload_links << preload_link
          end
          tag_options = {
            "src" => href,
            "crossorigin" => crossorigin
          }.merge!(options)
          if tag_options["nonce"] == true
            tag_options["nonce"] = content_security_policy_nonce
          end
          content_tag("script", "", tag_options)
        }.join("\n").html_safe

        if preload_links_header
          send_preload_links_header(preload_links)
        end

        sources_tags
      end
πŸ”Ž See on GitHub

Returns a link tag that browsers can use to preload the source. The source can be the path of a resource managed by asset pipeline, a full path, or an URI.

  • :type - Override the auto-generated mime type, defaults to the mime type for source extension.

  • :as - Override the auto-generated value for as attribute, calculated using source extension and mime type.

  • :crossorigin - Specify the crossorigin attribute, required to load cross-origin resources.

  • :nopush - Specify if the use of server push is not desired for the resource. Defaults to false.

  • :integrity - Specify the integrity attribute.

preload_link_tag("custom_theme.css")
# => <link rel="preload" href="/assets/custom_theme.css" as="style" type="text/css" />

preload_link_tag("/videos/video.webm")
# => <link rel="preload" href="/videos/video.mp4" as="video" type="video/webm" />

preload_link_tag(post_path(format: :json), as: "fetch")
# => <link rel="preload" href="/posts.json" as="fetch" type="application/json" />

preload_link_tag("worker.js", as: "worker")
# => <link rel="preload" href="/assets/worker.js" as="worker" type="text/javascript" />

preload_link_tag("//example.com/font.woff2")
# => <link rel="preload" href="//example.com/font.woff2" as="font" type="font/woff2" crossorigin="anonymous"/>

preload_link_tag("//example.com/font.woff2", crossorigin: "use-credentials")
# => <link rel="preload" href="//example.com/font.woff2" as="font" type="font/woff2" crossorigin="use-credentials" />

preload_link_tag("/media/audio.ogg", nopush: true)
# => <link rel="preload" href="/media/audio.ogg" as="audio" type="audio/ogg" />
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 296
      def preload_link_tag(source, options = {})
        href = path_to_asset(source, skip_pipeline: options.delete(:skip_pipeline))
        extname = File.extname(source).downcase.delete(".")
        mime_type = options.delete(:type) || Template::Types[extname]&.to_s
        as_type = options.delete(:as) || resolve_link_as(extname, mime_type)
        crossorigin = options.delete(:crossorigin)
        crossorigin = "anonymous" if crossorigin == true || (crossorigin.blank? && as_type == "font")
        integrity = options[:integrity]
        nopush = options.delete(:nopush) || false

        link_tag = tag.link(**{
          rel: "preload",
          href: href,
          as: as_type,
          type: mime_type,
          crossorigin: crossorigin
        }.merge!(options.symbolize_keys))

        preload_link = "<#{href}>; rel=preload; as=#{as_type}"
        preload_link += "; type=#{mime_type}" if mime_type
        preload_link += "; crossorigin=#{crossorigin}" if crossorigin
        preload_link += "; integrity=#{integrity}" if integrity
        preload_link += "; nopush" if nopush

        send_preload_links_header([preload_link])

        link_tag
      end
πŸ”Ž See on GitHub

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. For historical reasons, the 'media' attribute will always be present and defaults to β€œscreen”, so you must explicitly set it to β€œall” for the stylesheet(s) to apply to all media types.

If the server supports Early Hints header links for these assets will be automatically pushed.

stylesheet_link_tag "style"
# => <link href="/assets/style.css" media="screen" rel="stylesheet" />

stylesheet_link_tag "style.css"
# => <link href="/assets/style.css" media="screen" rel="stylesheet" />

stylesheet_link_tag "http://www.example.com/style.css"
# => <link href="http://www.example.com/style.css" media="screen" rel="stylesheet" />

stylesheet_link_tag "style", media: "all"
# => <link href="/assets/style.css" media="all" rel="stylesheet" />

stylesheet_link_tag "style", media: "print"
# => <link href="/assets/style.css" media="print" rel="stylesheet" />

stylesheet_link_tag "random.styles", "/css/stylish"
# => <link href="/assets/random.styles" media="screen" rel="stylesheet" />
#    <link href="/css/stylish.css" media="screen" rel="stylesheet" />
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 151
      def stylesheet_link_tag(*sources)
        options = sources.extract_options!.stringify_keys
        path_options = options.extract!("protocol", "host", "skip_pipeline").symbolize_keys
        preload_links = []
        crossorigin = options.delete("crossorigin")
        crossorigin = "anonymous" if crossorigin == true
        nopush = options["nopush"].nil? ? true : options.delete("nopush")
        integrity = options["integrity"]

        sources_tags = sources.uniq.map { |source|
          href = path_to_stylesheet(source, path_options)
          if preload_links_header
            preload_link = "<#{href}>; rel=preload; as=style"
            preload_link += "; crossorigin=#{crossorigin}" unless crossorigin.nil?
            preload_link += "; integrity=#{integrity}" unless integrity.nil?
            preload_link += "; nopush" if nopush
            preload_links << preload_link
          end
          tag_options = {
            "rel" => "stylesheet",
            "media" => "screen",
            "crossorigin" => crossorigin,
            "href" => href
          }.merge!(options)
          tag(:link, tag_options)
        }.join("\n").html_safe

        if preload_links_header
          send_preload_links_header(preload_links)
        end

        sources_tags
      end
πŸ”Ž See on GitHub

video_tag(*sources)

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 exist in your public videos directory.

Options

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

  • :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 β€œ{Width}x{Height}” or β€œ{Number}”, so β€œ30x45” becomes width=β€œ30” and height=β€œ45”, and β€œ50” becomes width=β€œ50” and height=β€œ50”. :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>
πŸ“ Source code 
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 431
      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
πŸ”Ž See on GitHub