Preloadables

Preloadables is a Rails gem exposing a set of view helpers for outputting HTML metadata related to domains, assets and pages that you would like to preload/prerender. Adding these links to your can dramatically speed up your website by directing the browser to perform certain actions before they're needed.

A word of caution: while preloading assets and prerendering pages is a brilliant technology that can dramatically speed up your website it can consume a ton of local resources and make too many network requests on connections that are bandwidth limited. I strongly encourage you to only preload assets that you're very confident the visitor will need soon and definitely only prerender a page if you're certain the visitor will go there next.

Installation

Add gem 'preloadables' to your Gemfile or if you're using gemspec:

Gem::Specification.new do |s|
  s.add_dependency 'preloadables'
end

Usage

<!-- in your views/layouts/layout.html.erb or maybe an _head.html.erb partial -->
<doctype html>
<html>
  <head>
    <title>my webpage</title>

    <%= preloadables_meta(@preloadables) %>

    <!-- stylesheet links, js, etc... -->
  </head>

  <body>
    <!-- site content... -->
  </body>
</html>

# in your controllers/my_app/application_controller.rb controller or other route controller
module MyApp

  def show
    @preloadables = {
      domains: [
        'my.asset.subdomain.com'
      ],
      assets: [
        '/assets/js/application_helper.js',
        '/assets/stylesheets/contact_page.css'
      ],
      pages: [
        '/page_2.html'
      ]
    }

    render :show, layout: 'my_app/layout'
  end

end

Methods

preloadable_meta is the main method and takes a hash of arguments for outputting all 3 kinds of preloading meta tags. If you prefer, you can also use one of the 3 other methods for more specific control.

preloadable_meta

Takes a hash with properties domains, assets and pages(all of which are arrays) and outputs relevant meta tags for each of them.

preload_domains_meta

Takes an array of domains to prefetch dns for.

preload_assets_meta

Takes an array of asset urls to prefetch.

prerender_pages_meta

Takes an array of page urls to prerender.

Development

Clone the repo
Run gem install bundler
Run bundle
Make sure everything works by running bundle exec rake
Make your changes in the tests and documentation and then the code
Commit changes, push them up to a branch and make a pull request

Testing

The default rake task includes running the tests so a simple rake on the command line with run the test suite.

License

This project is released under a Creative Commons Attribution-ShareAlike license. This requires that you both credit the original author and open source your own project. Long live open source software!

jacopotarantino/preloadables