name: dialog-patterns description: Native HTML dialog patterns for Rails with Turbo and Stimulus. Use when building modals, confirmations, alerts, or any overlay UI. Triggers on modal, dialog, popup, confirmation, alert, or toast patterns.

Native Dialog Patterns for Rails

Build accessible, modern dialog UIs using the native HTML <dialog> element with Turbo Frames and Stimulus. No JavaScript frameworks or heavy libraries required.

When to Use This Skill

Building modal dialogs for forms, confirmations, or content
Creating toast/alert notifications
Implementing confirmation dialogs (delete, destructive actions)
Any overlay UI that needs focus management and accessibility

Why Native `<dialog>`?

Feature	Native `<dialog>`	Custom Modal
Focus trapping	Built-in	Manual implementation
ESC to close	Built-in	Manual implementation
Backdrop	Built-in (`::backdrop`)	Manual overlay
Accessibility	Native `role="dialog"`	Manual ARIA
Top layer	Automatic (above all content)	z-index battles
Scroll lock	Automatic	Manual `overflow: hidden`

Core Pattern: Async Modal with Turbo Frames

The recommended pattern for Rails modals combines three technologies:

Turbo Frame - Async content loading without page reload
Native <dialog> - Accessible modal presentation
Stimulus controller - Lifecycle management

Step 1: Layout Container

Add a modal turbo-frame to your layout:

<%# app/views/layouts/application.html.erb %>
<body>
  <%= yield %>

  <%# Modal injection point %>
  <%= turbo_frame_tag :modal %>
</body>

Step 2: Trigger Links

Target the modal frame from any link:

<%# Any view %>
<%= link_to "New Post", new_post_path, data: { turbo_frame: :modal } %>
<%= link_to "Edit", edit_post_path(@post), data: { turbo_frame: :modal } %>
<%= link_to "Confirm Delete", confirm_delete_post_path(@post), data: { turbo_frame: :modal } %>

Step 3: Modal Content View

Wrap modal content in matching turbo-frame with nested inner frame:

<%# app/views/posts/new.html.erb %>
<%= turbo_frame_tag :modal do %>
  <%# Inner frame prevents flash during form validation %>
  <%= turbo_frame_tag :modal_content do %>
    <dialog data-controller="dialog" data-action="click->dialog#clickOutside" open>
      <article>
        <header>
          <h2>New Post</h2>
          <button data-action="dialog#close" aria-label="Close">&times;</button>
        </header>

        <%= render "form", post: @post %>
      </article>
    </dialog>
  <% end %>
<% end %>

Step 4: Stimulus Controller

// app/javascript/controllers/dialog_controller.js
import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  connect() {
    // Auto-open when content loads via Turbo
    this.element.showModal()

    // Store original scroll position
    this.scrollY = window.scrollY
  }

  disconnect() {
    // Clean up turbo-frame to prevent stale content flash
    const frame = this.element.closest("turbo-frame")
    if (frame) {
      frame.removeAttribute("src")
      // Safe DOM clearing without innerHTML
      frame.replaceChildren()
    }
  }

  close() {
    this.element.close()
  }

  clickOutside(event) {
    // Close when clicking backdrop (the dialog element itself, not content)
    if (event.target === this.element) {
      this.close()
    }
  }

  // Handle ESC key (native behavior, but can customize)
  keydown(event) {
    if (event.key === "Escape") {
      this.close()
    }
  }
}

Step 5: Styling

/* app/assets/stylesheets/components/dialog.css */
dialog {
  border: none;
  border-radius: 0.5rem;
  padding: 0;
  max-width: 32rem;
  width: 90vw;
  box-shadow: 0 25px 50px -12px rgb(0 0 0 / 0.25);
}

dialog::backdrop {
  background: rgb(0 0 0 / 0.5);
  backdrop-filter: blur(2px);
}

dialog article {
  padding: 1.5rem;
}

dialog header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

/* Prevent background scroll when modal open */
body:has(dialog[open]) {
  overflow: hidden;
}

With Tailwind:

<dialog class="rounded-lg shadow-xl max-w-lg w-[90vw] p-0 backdrop:bg-black/50 backdrop:backdrop-blur-sm"
        data-controller="dialog"
        data-action="click->dialog#clickOutside">
  <!-- content -->
</dialog>

Why Nested Turbo Frames?

The nested frame pattern (modal > modal_content) prevents content flashing:

<%= turbo_frame_tag :modal do %>
  <%= turbo_frame_tag :modal_content do %>
    <dialog>...</dialog>
  <% end %>
<% end %>

Problem without nested frame: When a form inside the modal has validation errors and re-renders, the outer frame briefly shows the old content before replacing it.

Solution with nested frame: The inner frame handles form re-renders independently, keeping the modal structure stable.

Form Handling in Modals

Successful Submission

Redirect with Turbo to close modal and update page:

# app/controllers/posts_controller.rb
def create
  @post = Post.new(post_params)

  if @post.save
    redirect_to posts_path, notice: "Post created!"
  else
    render :new, status: :unprocessable_entity
  end
end

The redirect navigates _top (full page), effectively closing the modal.

Validation Errors

Re-render the form with 422 status to keep modal open:

render :new, status: :unprocessable_entity

Turbo Stream Response (Stay in Modal)

To update content without closing:

def create
  @post = Post.new(post_params)

  if @post.save
    respond_to do |format|
      format.turbo_stream {
        render turbo_stream: [
          turbo_stream.append("posts", partial: "posts/post", locals: { post: @post }),
          turbo_stream.update("modal", "")  # Clear modal
        ]
      }
      format.html { redirect_to posts_path }
    end
  else
    render :new, status: :unprocessable_entity
  end
end

Confirmation Dialog Pattern

For destructive actions like delete:

The View

<%# app/views/posts/confirm_delete.html.erb %>
<%= turbo_frame_tag :modal do %>
  <dialog data-controller="dialog" data-action="click->dialog#clickOutside" open>
    <article>
      <h2>Delete Post?</h2>
      <p>Are you sure you want to delete "<%= @post.title %>"? This cannot be undone.</p>

      <footer class="flex gap-2 justify-end mt-4">
        <button data-action="dialog#close" class="btn btn-secondary">
          Cancel
        </button>
        <%= button_to "Delete", @post,
              method: :delete,
              class: "btn btn-danger",
              data: { turbo_confirm: false } %>
      </footer>
    </article>
  </dialog>
<% end %>

The Route

# config/routes.rb
resources :posts do
  member do
    get :confirm_delete
  end
end

The Trigger

<%= link_to "Delete", confirm_delete_post_path(@post), data: { turbo_frame: :modal } %>

Alert/Toast Pattern

For flash messages and notifications:

Stimulus Controller

// app/javascript/controllers/toast_controller.js
import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  static values = {
    duration: { type: Number, default: 5000 },
    dismissible: { type: Boolean, default: true }
  }

  connect() {
    this.element.showModal()

    if (this.durationValue > 0) {
      this.timeout = setTimeout(() => this.dismiss(), this.durationValue)
    }
  }

  disconnect() {
    clearTimeout(this.timeout)
  }

  dismiss() {
    this.element.close()
    this.element.remove()
  }
}

Toast Component

<%# app/views/shared/_toast.html.erb %>
<dialog class="toast toast-<%= type %>"
        data-controller="toast"
        data-toast-duration-value="<%= duration || 5000 %>"
        data-toast-dismissible-value="true"
        data-action="click->toast#dismiss">
  <p><%= message %></p>
</dialog>

Styling (Non-Modal Toast)

/* Position as fixed notification, not centered modal */
dialog.toast {
  position: fixed;
  bottom: 1rem;
  right: 1rem;
  margin: 0;
  padding: 1rem;
  border-radius: 0.5rem;
}

dialog.toast::backdrop {
  display: none;  /* No backdrop for toasts */
}

dialog.toast-success { background: #10b981; color: white; }
dialog.toast-error { background: #ef4444; color: white; }
dialog.toast-warning { background: #f59e0b; color: white; }
dialog.toast-info { background: #3b82f6; color: white; }

Using `show()` vs `showModal()`

showModal() - Centers dialog, adds backdrop, traps focus (use for modals)
show() - Opens without backdrop or focus trap (use for toasts/alerts)

// For toasts, use show() not showModal()
connect() {
  this.element.show()  // Non-modal, no backdrop
}

Slideover Panel Pattern

For side panels (settings, filters, details):

<dialog class="slideover"
        data-controller="dialog"
        data-action="click->dialog#clickOutside">
  <aside>
    <header>
      <h2>Filters</h2>
      <button data-action="dialog#close">&times;</button>
    </header>
    <div class="slideover-content">
      <%= render "filters" %>
    </div>
  </aside>
</dialog>

dialog.slideover {
  margin: 0;
  margin-left: auto;
  height: 100vh;
  max-height: 100vh;
  width: 24rem;
  max-width: 90vw;
  border-radius: 0;
}

dialog.slideover[open] {
  animation: slide-in 0.2s ease-out;
}

@keyframes slide-in {
  from { transform: translateX(100%); }
  to { transform: translateX(0); }
}

Accessibility Checklist

Native <dialog> handles most accessibility, but verify:

Focus management - First focusable element receives focus on open
Focus trap - Tab cycling stays within dialog (native behavior)
ESC closes - Native behavior with showModal()
Background inert - Content behind dialog is not interactive (native)
Visible close button - Not just ESC, provide visible control
Descriptive title - Use <h2> or aria-labelledby
Return focus - Focus returns to trigger element on close

Enhanced Accessibility

<dialog aria-labelledby="dialog-title"
        aria-describedby="dialog-description"
        data-controller="dialog">
  <h2 id="dialog-title">Confirm Action</h2>
  <p id="dialog-description">This action cannot be undone.</p>
  <!-- content -->
</dialog>

Focus Return

// Enhanced dialog controller with focus return
connect() {
  this.previouslyFocused = document.activeElement
  this.element.showModal()
}

close() {
  this.element.close()
  this.previouslyFocused?.focus()
}

Common Patterns Summary

Pattern	Container	Stimulus	`show` method
Modal form	`turbo_frame_tag :modal`	`dialog`	`showModal()`
Confirmation	`turbo_frame_tag :modal`	`dialog`	`showModal()`
Toast/Alert	Fixed position	`toast`	`show()`
Slideover	`turbo_frame_tag :modal`	`dialog`	`showModal()`

Anti-Patterns to Avoid

Anti-Pattern	Problem	Solution
Custom modal without `<dialog>`	No native accessibility	Use native `<dialog>`
Missing nested turbo-frame	Content flash on validation	Add inner frame
Not clearing frame on close	Stale content on reopen	Clear with `replaceChildren()` in `disconnect()`
z-index for stacking	Battles with other elements	`<dialog>` uses top layer
Manual focus trap	Complex, error-prone	`showModal()` handles it
Inline backdrop div	Extra markup	Use `::backdrop` pseudo-element

Testing Dialogs

# System test - use `within "dialog"` to scope assertions
within "dialog" do
  fill_in "Title", with: "My Post"
  click_button "Create"
end
expect(page).not_to have_selector("dialog[open]")  # Modal closed

Browser Support

Native <dialog> is supported in all modern browsers (Chrome 37+, Firefox 98+, Safari 15.4+, Edge 79+). For older browsers, include the dialog polyfill.

dialog-patterns