PlugEarlyHints

Convenience plug for sending HTTP 103 Early Hints.

This is useful for static resources that will be for sure required by the resulting page. For example you can use it for informing the client that you will need CSS later, so it can start fetching it right now.

Installation

def deps do
  [
    {:plug_early_hints, "~> 0.1.0"}
  ]
end

Usage

plug PlugEarlyHints,
  # List all resources that will be needed later when rendering page
  paths: [
    # External resources that will be connected to as we will use
    # different resources from it. It will speedup as the TLS handshake
    # will be already ended, so we will be able to fetch resources
    # right away
    "https://gravatar.com/": [rel: "dns-prefetch"],
    "https://gravatar.com/": [rel: "preconnect"],
    # "Regular" resources. We need to set `:as` to inform the client
    # (browser) what kinf of resource it is, so it will be able to
    # properly connect them
    "/css/app.css": [rel: "preload", as: "style"],
    "/js/app.js": [rel: "preload", as: "script"],
    # Preloading fonts will require additional `:type` and `:crossorgin`
    # to allow CSS engine to properly detect when apply the resource as
    # well as to prevent double load.
    "/fonts/recursive.woff2": [
      rel: "preload",
      as: "font",
      crossorgin: :anonymous,
      type: "font/woff2"
    ]
  ]

For more information about available options check out MDN Link.

License

See LICENSE.