Skeleton Loader is a Ruby on Rails gem for creating animated placeholders that enhance loading states. Whether rendered through Rails views or dynamically with JavaScript, these skeletons provide a seamless visual experience while content loads.

⚠ Note: Skeleton Loader is an experimental gem currently in early development, exploring the possibilities in the magical world of Rails gems. While loaders are ideally handled client-side, this gem aims to make it easy to add placeholders directly within the Rails realm.

• Features
• Installation
• Quick Start
• Usage
• JavaScript Integration
• Configuration
• Code Quality
• Roadmap
• Contributing
• License

• 🚀 Seamless Rails integration: Enhances loading transitions with minimal setup.
• 🔨 Universal skeletons: Creates loading states in Rails views & JavaScript.
• ⚙️ Consistency: Unified templates & options across both environments.
• ⚡ Lightweight & fast: Designed to be fast and easy to implement with minimal dependencies.

To install Skeleton Loader, add the following line to your Gemfile:

gem "skeleton-loader"

Then, execute:

bundle install

• Ruby 2.5 or higher
• Rails 5.0 or higher
• Asset Pipeline (for CSS handling)

Add predefined templates to your app with:

rails generate skeleton_loader:add_templates

This command will place templates in app/views/skeleton_loader/, which you can customize as needed.

And in case needed, you can revert to default templates by running:

rails generate skeleton_loader:reset_templates

Quickly integrate Skeleton Loader into your Rails app with these steps:

1. Include Assets

   • Rails 7 (Import Maps):

     • In config/importmap.rb, add:

       pin "skeleton-loader", to: "skeleton_loader.js"

     • In your JavaScript entry file, add:

       import SkeletonLoader from "skeleton-loader"

   • In app/assets/stylesheets/application.css, add:

     *= require skeleton_loader

   • Rails 6 (Webpack):

     • Run:

       npm install "@ersync/skeleton-loader"

     • In your JavaScript entry file, add:

       import SkeletonLoader from "skeleton-loader"

   • Rails 5 (Asset Pipeline):

     • In app/assets/javascripts/application.js, add:

       //= require skeleton_loader

     • In app/assets/stylesheets/application.css, add:

       *= require skeleton_loader

2. Use in Views

   Use the skeleton_loader helper next to the content that loads slowly. Set content_id to the target element's ID and choose a type for the skeleton template.

   Example:

   <div id="content-element">
     <!-- Content that takes time to load -->
   </div>
   <%= skeleton_loader(content_id: 'content-element', type: "card") %>

For more detailed instructions, refer to Usage section.

The gem provides a primary view helper, skeleton_loader, which generates a div containing a skeleton next to the targeted content element. This skeleton will be hidden once the content element fully loads, providing a seamless loading experience.

Specify content_id and, optionally, a template type and customization options.

<%= skeleton_loader(content_id: 'content-element', 
  type: "card",
  count: 5,
  scale: 1.2,
  animation_type: 'animation-pulse') %>

Define your own HTML structure in a block. Note that type and options are not used.

<%= skeleton_loader(content_id: 'content-element') do %>
  <div class="custom-skeleton">
    <div class="avatar skeleton-circle"></div>
    <div class="text-lines"></div>
  </div>
<% end %>

See Configuration for all available options.

Skeleton Loader also provides a JavaScript API to dynamically create skeletons independently of Rails views.

const skeleton = new SkeletonLoader();

const loader = skeleton.render({
  contentId,                    // Required. ID of the element to replace with skeleton
  ...options                    // Optional. See configuration section for available options
});

const loader = skeleton.renderCustom({
  contentId,                    // Required. ID of the element to replace with skeleton
  markup                        // Required. Custom HTML string for skeleton content
});

// Check if still loading
if (loader.isLoading()) {
  // Do something while content loads
}

// Remove skeleton and show content
loader.reveal();

async function loadUserProfile(userId) {
  // Create skeleton while loading
  const loader = skeleton.render({
    contentId: 'content-element',
    type: 'profile'
  });

  try {
    // Fetch your data
    const response = await fetch(`/api/users/${userId}`);
    const userData = await response.json();

    // Update the DOM with your content
    document.getElementById('content-element').innerHTML = createUserProfile(userData);

    // Remove the skeleton
    loader.reveal();
  } catch (error) {
    console.error('Failed to load user profile:', error);
    loader.reveal(); // Always cleanup the skeleton
  }
}

async function loadDashboard() {
  // Create multiple skeletons
  const loaders = {
    profile: skeleton.render({ contentId: 'profile', type: 'profile', scale:1.2, width:250 }),
    stats: skeleton.render({ contentId: 'stats', type: 'card', scale:1.3, animationType:"sl-flow" }),
    activities: skeleton.render({ contentId: 'activities', type: 'list' })
  };

  // Load your data
  const [profileData, statsData, activitiesData] = await Promise.all([
    fetchProfile(),
    fetchStats(),
    fetchActivities()
  ]);

  // Update content and reveal each section
  updateProfile(profileData);
  loaders.profile.reveal();

  updateStats(statsData);
  loaders.stats.reveal();

  updateActivities(activitiesData);
  loaders.activities.reveal();
}

The following options can be passed to both the Rails view helper and JavaScript API. Note that Rails uses snake_case (e.g., animation_type), while JavaScript uses camelCase (e.g., animationType).

Notes:

• type determines default layout and styling
• scale affects width and spacing proportionally
• animation_type supports different loading effect styles

Skeleton Loader comes with several pre-built templates, each with their default configurations:

For an interactive preview of available templates and animations, visit the Live Demo.

Choose from several animation styles to match your design:

• sl-gradient (default): Smooth gradient movement
• sl-shine: Shimmer effect
• sl-pulse: Fade in/out
• sl-flow: Continuous flow
• sl-neon: Subtle glow
• sl-breathing: Gentle scaling

To set application-wide defaults, create config/initializers/skeleton_loader.rb:

SkeletonLoader.configure do |config|
  # Override default template settings
  config.templates[:product] = {
          width: 400,
          count: 6,
          per_row: 3
  }
  # Global settings
  config.scale = 1.0                     # Default: 1.0
  config.animation_type = "sl-gradient"  # Default: "sl-gradient"
end

For applications requiring custom HTML elements or styles:

SkeletonLoader.configure do |config|
  config.additional_allowed_tags = []                  # Default: []
  config.additional_allowed_attributes = {}            # Default: {}
  config.additional_allowed_css_properties = []        # Default: []
end

Skeleton Loader maintains code quality through:

• RSpec: Comprehensive tests covering core functionality.
• CircleCI: Continuous integration ensures all new changes meet quality standards.
• Rubocop: Consistent linting aligns code with Ruby community conventions.

Here are some features I'd like to add when I have time:

• New Templates & Animations: Expanding template and animation options.
• Turbo & Stimulus Support: Enhancing compatibility with Rails Turbo and StimulusJS.
• Builder Helper for Custom Skeletons:: Introducing a helper to easily create custom skeletons (e.g., circles, rectangles, etc.) with customizable options, simplifying the process of designing custom skeletons.

Suggestions and contributions are welcome!

To contribute:

1. Fork the repository.
2. Create a new feature branch.
3. Add tests for new features.
4. Commit your changes and submit a pull request.

Please follow the Code of Conduct for all contributions.

Skeleton Loader is licensed under the MIT License. See LICENSE for details.