method

preload_link_tag

v6.0.0 - Show latest stable - 0 notes - Class: ActionView::Helpers::AssetTagHelper

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What's this?

preload_link_tag(source, options = {}) public

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.

Options

: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.

Examples

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" />

Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 268
      def preload_link_tag(source, options = {})
        href = asset_path(source, skip_pipeline: options.delete(:skip_pipeline))
        extname = File.extname(source).downcase.delete(".")
        mime_type = options.delete(:type) || Template::Types[extname].try(: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")
        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))

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

        request.send_early_hints("Link" => early_hints_link) if respond_to?(:request) && request

        link_tag
      end

preload_link_tag

Related methods

Options

Examples