accessibility

Accessibility (a11y) — Drupal Development

Activation

Activate when:

• Working on Twig templates, frontend components, or theme development
• User mentions accessibility, a11y, WCAG, ARIA, screen reader, keyboard navigation
• Creating forms, interactive elements, modals, or dynamic content
• Reviewing frontend code for compliance

WCAG 2.2 Quick Reference

Level	Target	Criteria Count	Typical Requirement
A	Minimum	30	Legal baseline in most jurisdictions
AA	Standard	24 additional	Target this — industry standard, most regulations
AAA	Enhanced	28 additional	Rarely required site-wide, useful for specific content

Core Principles (POUR)

1. Perceivable — content available to all senses (alt text, captions, contrast)
2. Operable — navigable by keyboard, enough time, no seizure triggers
3. Understandable — readable, predictable, input assistance
4. Robust — compatible with assistive technologies

Semantic HTML in Drupal Twig

Heading Hierarchy

{# CORRECT: proper heading hierarchy #}
<article{{ attributes }}>
  <h2{{ title_attributes }}>{{ label }}</h2>
  <div{{ content_attributes }}>
    <h3>Section Title</h3>
    <p>{{ content.field_body }}</p>
  </div>
</article>

{# WRONG: skipping heading levels #}
<div>
  <h1>Title</h1>
  <h4>Subsection</h4> {# Skipped h2 and h3! #}
</div>

Landmarks

{# page.html.twig with proper landmarks #}
<header role="banner">
  {{ page.header }}
</header>

<nav role="navigation" aria-label="{{ 'Main navigation'|t }}">
  {{ page.primary_menu }}
</nav>

<main role="main" id="main-content">
  <a id="main-content-anchor" tabindex="-1"></a>
  {{ page.content }}
</main>

<aside role="complementary" aria-label="{{ 'Sidebar'|t }}">
  {{ page.sidebar }}
</aside>

<footer role="contentinfo">
  {{ page.footer }}
</footer>

Accessible Navigation

{# menu.html.twig — accessible menu with current page indication #}
{% import _self as menus %}

{{ menus.menu_links(items, attributes, 0) }}

{% macro menu_links(items, attributes, menu_level) %}
  {% import _self as menus %}
  {% if items %}
    <ul{{ attributes.addClass(menu_level == 0 ? 'menu' : 'menu--child') }} role="list">
      {% for item in items %}
        {% set item_classes = [
          'menu__item',
          item.in_active_trail ? 'menu__item--active-trail',
          item.below ? 'menu__item--expanded',
        ] %}
        <li{{ item.attributes.addClass(item_classes) }}>
          <a href="{{ item.url }}"
            {{ item.in_active_trail ? 'aria-current="page"' }}
            {{ item.below ? 'aria-expanded="false" aria-haspopup="true"' }}>
            {{ item.title }}
          </a>
          {% if item.below %}
            {{ menus.menu_links(item.below, attributes.removeClass(attributes.class), menu_level + 1) }}
          {% endif %}
        </li>
      {% endfor %}
    </ul>
  {% endif %}
{% endmacro %}

ARIA Patterns

Rule: Use ARIA as Last Resort

1. Use native HTML first (<button>, <nav>, <dialog>)
2. Don't change native semantics (<h2 role="tab"> — wrong)
3. All interactive ARIA controls must be keyboard operable
4. Don't use role="presentation" or aria-hidden="true" on focusable elements
5. All interactive elements must have accessible names

Common ARIA Patterns in Drupal

{# Accessible dropdown / disclosure #}
<div class="dropdown">
  <button
    aria-expanded="false"
    aria-controls="dropdown-menu-{{ id }}"
    type="button">
    {{ label }}
  </button>
  <ul id="dropdown-menu-{{ id }}" role="menu" hidden>
    {% for item in items %}
      <li role="menuitem">
        <a href="{{ item.url }}">{{ item.title }}</a>
      </li>
    {% endfor %}
  </ul>
</div>

{# Accessible tabs #}
<div class="tabs">
  <ul role="tablist" aria-label="{{ 'Content sections'|t }}">
    {% for tab in tabs %}
      <li role="presentation">
        <button
          role="tab"
          id="tab-{{ tab.id }}"
          aria-controls="panel-{{ tab.id }}"
          aria-selected="{{ loop.first ? 'true' : 'false' }}"
          tabindex="{{ loop.first ? '0' : '-1' }}">
          {{ tab.label }}
        </button>
      </li>
    {% endfor %}
  </ul>
  {% for tab in tabs %}
    <div
      role="tabpanel"
      id="panel-{{ tab.id }}"
      aria-labelledby="tab-{{ tab.id }}"
      {{ not loop.first ? 'hidden' }}
      tabindex="0">
      {{ tab.content }}
    </div>
  {% endfor %}
</div>

{# Live region for dynamic updates #}
<div aria-live="polite" aria-atomic="true" class="visually-hidden">
  {{ status_message }}
</div>

Keyboard Navigation

Requirements

Element	Expected Keyboard Behavior
Links/buttons	Enter to activate, visible focus indicator
Menus	Arrow keys to navigate, Escape to close
Tabs	Arrow keys between tabs, Tab to enter panel
Modals/dialogs	Focus trapped inside, Escape to close, focus returns on close
Carousels	Arrow keys, pause on focus, button to stop auto-play
Autocomplete	Arrow keys to navigate, Enter to select, Escape to dismiss

Focus Management in JavaScript

(function (Drupal) {
  'use strict';

  Drupal.behaviors.accessibleModal = {
    attach(context) {
      const triggers = once('a11y-modal', '[data-modal-trigger]', context);

      triggers.forEach((trigger) => {
        trigger.addEventListener('click', (e) => {
          const modal = document.getElementById(trigger.dataset.modalTrigger);
          if (!modal) return;

          // Store trigger to return focus on close
          modal._triggerElement = trigger;

          // Show and trap focus
          modal.showModal();
          const firstFocusable = modal.querySelector(
            'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
          );
          firstFocusable?.focus();
        });
      });

      // Return focus on close
      once('a11y-modal-close', 'dialog', context).forEach((dialog) => {
        dialog.addEventListener('close', () => {
          dialog._triggerElement?.focus();
        });
      });
    },
  };
})(Drupal);

Skip Link

{# Must be first focusable element in page.html.twig #}
<a href="#main-content" class="visually-hidden focusable skip-link">
  {{ 'Skip to main content'|t }}
</a>

.skip-link {
  position: absolute;
  inset-block-start: -100%;
}
.skip-link:focus {
  position: fixed;
  inset-block-start: 0;
  inset-inline-start: 0;
  z-index: 1000;
  padding: var(--space-xs) var(--space-sm);
  background: var(--color-focus);
  color: var(--color-on-focus);
}

Color and Contrast

WCAG Contrast Ratios

Text Type	AA Ratio	AAA Ratio
Normal text (< 18pt)	4.5:1	7:1
Large text (≥ 18pt or 14pt bold)	3:1	4.5:1
UI components / graphical objects	3:1	—

CSS Patterns

/* Use custom properties for easy theme-wide contrast management */
:root {
  --color-text: #1a1a1a;          /* 15.3:1 on white */
  --color-text-muted: #595959;    /* 7.0:1 on white */
  --color-link: #0055b8;          /* 7.1:1 on white */
  --color-link-visited: #6b3fa0;  /* 5.6:1 on white */
  --color-focus: #1a73e8;
  --focus-outline: 3px solid var(--color-focus);
  --focus-outline-offset: 2px;
}

/* Consistent focus indicators — NEVER use outline: none without replacement */
:focus-visible {
  outline: var(--focus-outline);
  outline-offset: var(--focus-outline-offset);
}

/* High contrast mode support */
@media (forced-colors: active) {
  .button {
    border: 2px solid ButtonText;
  }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

Forms Accessibility

{# Accessible form field with error #}
<div class="form-item{{ errors ? ' form-item--error' }}">
  <label for="edit-email" class="form-item__label{{ required ? ' form-required' }}">
    {{ 'Email address'|t }}
    {% if required %}
      <span class="form-required__marker" aria-hidden="true">*</span>
    {% endif %}
  </label>

  {% if description %}
    <div id="edit-email-description" class="form-item__description">
      {{ description }}
    </div>
  {% endif %}

  <input
    type="email"
    id="edit-email"
    name="email"
    class="form-email{{ errors ? ' error' }}"
    {{ required ? 'required aria-required="true"' }}
    {{ description ? 'aria-describedby="edit-email-description"'|raw }}
    {{ errors ? 'aria-invalid="true" aria-errormessage="edit-email-error"'|raw }}
    autocomplete="email"
  />

  {% if errors %}
    <div id="edit-email-error" class="form-item__error-message" role="alert">
      {{ errors }}
    </div>
  {% endif %}
</div>

Images and Media

{# Informative image — describe the content #}
<img src="{{ file_url }}" alt="{{ image_alt }}" />

{# Decorative image — empty alt, not missing #}
<img src="{{ decorative_url }}" alt="" role="presentation" />

{# Complex image — long description #}
<figure>
  <img src="{{ chart_url }}" alt="{{ 'Chart showing quarterly revenue growth'|t }}"
       aria-describedby="chart-description-{{ id }}" />
  <figcaption id="chart-description-{{ id }}">
    {{ detailed_description }}
  </figcaption>
</figure>

{# Video with captions #}
<video controls>
  <source src="{{ video_url }}" type="video/mp4" />
  <track kind="captions" src="{{ captions_url }}" srclang="en" label="{{ 'English'|t }}" default />
  <track kind="descriptions" src="{{ descriptions_url }}" srclang="en" label="{{ 'Audio descriptions'|t }}" />
</video>

Dynamic Content — Drupal.announce()

(function (Drupal) {
  'use strict';

  Drupal.behaviors.liveUpdates = {
    attach(context) {
      once('live-filter', '.views-exposed-form', context).forEach((form) => {
        form.addEventListener('change', () => {
          // After AJAX completes, announce result count
          const resultCount = document.querySelectorAll('.views-row').length;
          Drupal.announce(
            Drupal.t('@count results found', { '@count': resultCount }),
            'polite'  // 'polite' waits, 'assertive' interrupts
          );
        });
      });
    },
  };
})(Drupal);

Status Messages

{# status-messages.html.twig #}
<div data-drupal-messages>
  {% for type, messages in message_list %}
    <div
      role="{{ type == 'error' ? 'alert' : 'status' }}"
      aria-label="{{ status_headings[type] }}"
      class="messages messages--{{ type }}">
      {% if status_headings[type] %}
        <h2 class="visually-hidden">{{ status_headings[type] }}</h2>
      {% endif %}
      {% if messages|length > 1 %}
        <ul class="messages__list">
          {% for message in messages %}
            <li class="messages__item">{{ message }}</li>
          {% endfor %}
        </ul>
      {% else %}
        <p class="messages__item">{{ messages|first }}</p>
      {% endif %}
    </div>
  {% endfor %}
</div>

Automated Testing

axe-core Integration

# Install
npm install --save-dev @axe-core/cli

# Run against local site
npx axe http://my-drupal-site.ddev.site --tags wcag2a,wcag2aa,wcag22aa

# With specific rules
npx axe http://my-drupal-site.ddev.site --rules color-contrast,label,image-alt

Lighthouse CI

# Install
npm install --save-dev @lhci/cli

# Run accessibility audit
npx lhci autorun --collect.url=http://my-drupal-site.ddev.site \
  --assert.assertions='categories:accessibility>=0.9'

pa11y

# Install and run
npm install --save-dev pa11y
npx pa11y http://my-drupal-site.ddev.site --standard WCAG2AA

# Multiple pages
npx pa11y-ci --config .pa11yci.json

PHPUnit (Drupal Functional Tests)

declare(strict_types=1);

namespace Drupal\Tests\my_module\Functional;

use Drupal\Tests\BrowserTestBase;

final class AccessibilityTest extends BrowserTestBase {

  protected $defaultTheme = 'stark';

  public function testPageHasProperHeadingHierarchy(): void {
    $this->drupalGet('/node/1');
    $session = $this->assertSession();

    // Check h1 exists exactly once
    $h1_elements = $this->getSession()->getPage()->findAll('css', 'h1');
    $this->assertCount(1, $h1_elements, 'Page has exactly one h1 element');

    // Check skip link exists
    $session->elementExists('css', 'a.skip-link');

    // Check images have alt attributes
    $images = $this->getSession()->getPage()->findAll('css', 'img');
    foreach ($images as $image) {
      $this->assertTrue(
        $image->hasAttribute('alt'),
        sprintf('Image %s missing alt attribute', $image->getAttribute('src'))
      );
    }

    // Check form labels
    $inputs = $this->getSession()->getPage()->findAll('css', 'input:not([type="hidden"])');
    foreach ($inputs as $input) {
      $id = $input->getAttribute('id');
      if ($id) {
        $session->elementExists('css', "label[for=\"{$id}\"]");
      }
    }
  }

}

Manual Testing Checklist

Keyboard-Only Navigation

• Tab through entire page — all interactive elements reachable
• Focus order matches visual order
• Focus indicator visible on every focused element
• Can operate all controls (buttons, links, menus, tabs, modals)
• Can dismiss overlays/modals with Escape
• No keyboard traps (can always Tab away)

Screen Reader (VoiceOver / NVDA)

• Page title announced on load
• Headings navigable (rotor/headings list)
• Landmarks navigable
• Form labels read correctly
• Error messages associated with fields
• Dynamic content changes announced
• Decorative images hidden, informative images described

Visual

• Zoom to 200% — no content cut off or overlapping
• Text spacing increased — still readable (letter-spacing 0.12em, word-spacing 0.16em, line-height 1.5)
• Windows High Contrast Mode — content visible
• Color not sole indicator of meaning (errors have icons/text too)

Common Drupal a11y Issues

Issue	Where	Fix
Views output missing headings	Views block/page	Add header with heading tag in views settings
Admin toolbar not keyboard accessible	Admin toolbar module	Use Gin theme which fixes this
AJAX updates not announced	Custom AJAX	Use Drupal.announce() after AJAX completes
Modal dialogs — focus not trapped	jQuery UI dialog	Use native <dialog> element or add focus trap JS
Dropdown menus — keyboard inaccessible	Custom menus	Add arrow key navigation + Escape handler
Status messages not role="status"	Custom templates	Use proper role="status" or role="alert"
Entity reference autocomplete	Core widget	Generally accessible, but test with screen reader
CKEditor content	WYSIWYG	Train editors on heading hierarchy, alt text, link text
Responsive tables	Views tables	Use <caption>, proper <th scope>, consider reflow pattern
Color picker fields	Custom forms	Provide text input alternative alongside visual picker