Accessibility A11y Enhanced Skill

You are an expert accessibility engineer specializing in WCAG compliance and inclusive web design. When asked to test or improve accessibility, follow these comprehensive instructions.

Core Principles (POUR)

1. Perceivable -- Information must be presentable to users in ways they can perceive.
2. Operable -- User interface components must be operable by all users.
3. Understandable -- Information and operation must be understandable.
4. Robust -- Content must be robust enough to work with assistive technologies.

WCAG 2.1 Compliance Levels

Level A (Minimum)
- Basic accessibility features
- Essential for some users
- Examples: Alt text, keyboard access, labels

Level AA (Standard)
- Recommended baseline for most sites
- Addresses major barriers
- Examples: Color contrast 4.5:1, focus indicators, skip links

Level AAA (Enhanced)
- Highest accessibility standard
- Not always achievable for all content
- Examples: Color contrast 7:1, sign language, extended descriptions

Setting Up Automated Testing

With Playwright and axe-core

// playwright.config.ts
import { defineConfig } from '@playwright/test';

export default defineConfig({
  use: {
    trace: 'on-first-retry',
    screenshot: 'only-on-failure',
  },
});

npm install --save-dev @axe-core/playwright

// tests/accessibility.spec.ts
import { test, expect } from '@playwright/test';
import AxeBuilder from '@axe-core/playwright';

test.describe('Accessibility tests', () => {
  test('should not have any automatically detectable accessibility issues', async ({ page }) => {
    await page.goto('/');

    const accessibilityScanResults = await new AxeBuilder({ page })
      .withTags(['wcag2a', 'wcag2aa', 'wcag21a', 'wcag21aa'])
      .analyze();

    expect(accessibilityScanResults.violations).toEqual([]);
  });

  test('should have accessible homepage', async ({ page }) => {
    await page.goto('/');

    const results = await new AxeBuilder({ page })
      .exclude('#third-party-widget') // Exclude third-party content
      .analyze();

    // Log violations for debugging
    if (results.violations.length > 0) {
      console.log('Accessibility violations:', JSON.stringify(results.violations, null, 2));
    }

    expect(results.violations).toEqual([]);
  });

  test('should have accessible forms', async ({ page }) => {
    await page.goto('/contact');

    const results = await new AxeBuilder({ page })
      .include('form') // Test only forms
      .analyze();

    expect(results.violations).toEqual([]);
  });

  test('should meet specific WCAG rules', async ({ page }) => {
    await page.goto('/');

    const results = await new AxeBuilder({ page })
      .withRules(['color-contrast', 'image-alt', 'label', 'aria-required-attr'])
      .analyze();

    expect(results.violations).toEqual([]);
  });
});

With Cypress and axe-core

// cypress/support/commands.ts
import 'cypress-axe';

Cypress.Commands.add('checkA11y', (context?: string, options?: any) => {
  cy.injectAxe();
  cy.checkA11y(context, options, (violations) => {
    if (violations.length) {
      cy.task('log', violations);
    }
  });
});

// cypress/e2e/accessibility.cy.ts
describe('Accessibility', () => {
  beforeEach(() => {
    cy.visit('/');
    cy.injectAxe();
  });

  it('should have no accessibility violations on homepage', () => {
    cy.checkA11y();
  });

  it('should have accessible navigation', () => {
    cy.checkA11y('nav');
  });

  it('should meet WCAG AA color contrast', () => {
    cy.checkA11y(null, {
      rules: {
        'color-contrast': { enabled: true },
      },
    });
  });
});

Manual Accessibility Testing

1. Keyboard Navigation Tests

test.describe('Keyboard navigation', () => {
  test('should navigate through interactive elements with Tab', async ({ page }) => {
    await page.goto('/');

    // Start at the first focusable element
    await page.keyboard.press('Tab');

    const firstFocusedElement = await page.evaluate(() => document.activeElement?.tagName);
    expect(['A', 'BUTTON', 'INPUT']).toContain(firstFocusedElement);

    // Tab through all interactive elements
    for (let i = 0; i < 5; i++) {
      await page.keyboard.press('Tab');
      const focused = await page.evaluate(() => {
        const el = document.activeElement;
        return {
          tag: el?.tagName,
          visible: el ? window.getComputedStyle(el).display !== 'none' : false,
        };
      });

      expect(focused.visible).toBe(true);
    }
  });

  test('should submit form with Enter key', async ({ page }) => {
    await page.goto('/contact');

    await page.fill('#name', 'Test User');
    await page.fill('#email', 'test@example.com');
    await page.fill('#message', 'Test message');

    // Focus on submit button and press Enter
    await page.focus('button[type="submit"]');
    await page.keyboard.press('Enter');

    await expect(page.getByText('Message sent')).toBeVisible();
  });

  test('should close modal with Escape key', async ({ page }) => {
    await page.goto('/');

    await page.click('button[aria-label="Open modal"]');
    await expect(page.getByRole('dialog')).toBeVisible();

    await page.keyboard.press('Escape');
    await expect(page.getByRole('dialog')).not.toBeVisible();
  });

  test('should skip to main content with skip link', async ({ page }) => {
    await page.goto('/');

    // Tab to skip link
    await page.keyboard.press('Tab');

    const skipLink = page.getByText('Skip to main content');
    await expect(skipLink).toBeFocused();

    // Activate skip link
    await page.keyboard.press('Enter');

    // Main content should now be focused
    const mainContent = page.locator('main');
    await expect(mainContent).toBeFocused();
  });
});

2. Focus Management Tests

test.describe('Focus management', () => {
  test('should have visible focus indicators', async ({ page }) => {
    await page.goto('/');

    await page.keyboard.press('Tab');
    const focusedElement = page.locator(':focus');

    // Check that focused element has visible outline or custom focus styles
    const styles = await focusedElement.evaluate((el) => {
      const computed = window.getComputedStyle(el);
      return {
        outline: computed.outline,
        outlineWidth: computed.outlineWidth,
        boxShadow: computed.boxShadow,
      };
    });

    // Should have either outline or box-shadow for focus
    expect(
      styles.outlineWidth !== '0px' ||
      styles.boxShadow !== 'none'
    ).toBe(true);
  });

  test('should trap focus inside modal', async ({ page }) => {
    await page.goto('/');

    await page.click('button[aria-label="Open modal"]');

    const modal = page.getByRole('dialog');
    await expect(modal).toBeVisible();

    // Tab through modal elements
    await page.keyboard.press('Tab');
    const firstFocusable = await page.evaluate(() => document.activeElement?.id);

    // Keep tabbing until we cycle back
    for (let i = 0; i < 10; i++) {
      await page.keyboard.press('Tab');
    }

    const currentFocus = await page.evaluate(() => document.activeElement?.id);

    // Focus should cycle within modal, not escape to body
    const focusedParent = await page.evaluate(() =>
      document.activeElement?.closest('[role="dialog"]') !== null
    );
    expect(focusedParent).toBe(true);
  });
});

3. Screen Reader Testing

test.describe('Screen reader support', () => {
  test('should have proper ARIA labels', async ({ page }) => {
    await page.goto('/');

    // Check navigation has aria-label
    const nav = page.locator('nav');
    const ariaLabel = await nav.getAttribute('aria-label');
    expect(ariaLabel).toBeTruthy();

    // Check buttons have accessible names
    const buttons = page.locator('button');
    const count = await buttons.count();

    for (let i = 0; i < count; i++) {
      const button = buttons.nth(i);
      const accessibleName = await button.evaluate((el) =>
        (el as HTMLElement).ariaLabel ||
        (el as HTMLElement).innerText ||
        (el as HTMLElement).title
      );
      expect(accessibleName).toBeTruthy();
    }
  });

  test('should announce page regions correctly', async ({ page }) => {
    await page.goto('/');

    // Check for landmark regions
    const landmarks = await page.evaluate(() => {
      return {
        header: document.querySelector('header')?.getAttribute('role') || 'banner',
        nav: document.querySelector('nav')?.getAttribute('role') || 'navigation',
        main: document.querySelector('main')?.getAttribute('role') || 'main',
        footer: document.querySelector('footer')?.getAttribute('role') || 'contentinfo',
      };
    });

    expect(landmarks.header).toBeTruthy();
    expect(landmarks.nav).toBeTruthy();
    expect(landmarks.main).toBeTruthy();
    expect(landmarks.footer).toBeTruthy();
  });

  test('should have accessible image alt text', async ({ page }) => {
    await page.goto('/');

    const images = page.locator('img');
    const count = await images.count();

    for (let i = 0; i < count; i++) {
      const img = images.nth(i);
      const alt = await img.getAttribute('alt');
      const role = await img.getAttribute('role');

      // Images should have alt text or role="presentation" for decorative images
      expect(alt !== null || role === 'presentation').toBe(true);
    }
  });

  test('should use ARIA live regions for dynamic content', async ({ page }) => {
    await page.goto('/notifications');

    // Trigger a notification
    await page.click('button[aria-label="Show notification"]');

    const liveRegion = page.locator('[aria-live="polite"]');
    await expect(liveRegion).toHaveText('Notification message');
  });
});

4. Color Contrast Tests

test.describe('Color contrast', () => {
  test('should meet WCAG AA contrast ratio for text', async ({ page }) => {
    await page.goto('/');

    const results = await new AxeBuilder({ page })
      .withRules(['color-contrast'])
      .analyze();

    expect(results.violations).toEqual([]);
  });

  test('should be readable in high contrast mode', async ({ page }) => {
    await page.emulateMedia({ colorScheme: 'dark', forcedColors: 'active' });
    await page.goto('/');

    // Check that text is visible
    const heading = page.getByRole('heading', { level: 1 });
    await expect(heading).toBeVisible();
  });
});

5. Form Accessibility Tests

test.describe('Form accessibility', () => {
  test('should have proper labels for inputs', async ({ page }) => {
    await page.goto('/contact');

    const inputs = page.locator('input, textarea, select');
    const count = await inputs.count();

    for (let i = 0; i < count; i++) {
      const input = inputs.nth(i);
      const id = await input.getAttribute('id');
      const ariaLabel = await input.getAttribute('aria-label');
      const ariaLabelledBy = await input.getAttribute('aria-labelledby');

      // Input should have associated label
      const hasLabel = id
        ? await page.locator(`label[for="${id}"]`).count() > 0
        : false;

      expect(hasLabel || ariaLabel || ariaLabelledBy).toBeTruthy();
    }
  });

  test('should show validation errors accessibly', async ({ page }) => {
    await page.goto('/contact');

    // Submit form without filling required fields
    await page.click('button[type="submit"]');

    // Error message should be announced
    const errorMessage = page.locator('[role="alert"]');
    await expect(errorMessage).toBeVisible();

    // Invalid field should have aria-invalid
    const emailInput = page.locator('#email');
    const ariaInvalid = await emailInput.getAttribute('aria-invalid');
    expect(ariaInvalid).toBe('true');

    // Error should be associated with field
    const ariaDescribedBy = await emailInput.getAttribute('aria-describedby');
    expect(ariaDescribedBy).toBeTruthy();
  });

  test('should have accessible required field indicators', async ({ page }) => {
    await page.goto('/contact');

    const requiredInputs = page.locator('[required]');
    const count = await requiredInputs.count();

    for (let i = 0; i < count; i++) {
      const input = requiredInputs.nth(i);
      const ariaRequired = await input.getAttribute('aria-required');

      expect(ariaRequired).toBe('true');
    }
  });
});

Common ARIA Patterns

1. Button Pattern

<!-- Good: Button with accessible name -->
<button aria-label="Close dialog">×</button>

<!-- Good: Button with text content -->
<button>Submit</button>

<!-- Bad: No accessible name -->
<button><span class="icon-close"></span></button>

2. Dialog/Modal Pattern

<!-- Modal with proper ARIA -->
<div
  role="dialog"
  aria-labelledby="modal-title"
  aria-describedby="modal-description"
  aria-modal="true"
>
  <h2 id="modal-title">Confirm Action</h2>
  <p id="modal-description">Are you sure you want to proceed?</p>
  <button>Confirm</button>
  <button>Cancel</button>
</div>

3. Tabs Pattern

test('should implement accessible tabs', async ({ page }) => {
  await page.goto('/tabs-demo');

  // Tab list should have role="tablist"
  const tablist = page.getByRole('tablist');
  await expect(tablist).toBeVisible();

  // Individual tabs should have role="tab"
  const firstTab = page.getByRole('tab', { name: 'Tab 1' });
  await expect(firstTab).toHaveAttribute('aria-selected', 'true');

  // Tab panels should have role="tabpanel"
  const firstPanel = page.getByRole('tabpanel', { name: 'Tab 1' });
  await expect(firstPanel).toBeVisible();

  // Arrow keys should navigate tabs
  await firstTab.focus();
  await page.keyboard.press('ArrowRight');

  const secondTab = page.getByRole('tab', { name: 'Tab 2' });
  await expect(secondTab).toBeFocused();
  await expect(secondTab).toHaveAttribute('aria-selected', 'true');
});

4. Combobox/Autocomplete Pattern

test('should implement accessible autocomplete', async ({ page }) => {
  await page.goto('/search');

  const combobox = page.getByRole('combobox');
  await expect(combobox).toHaveAttribute('aria-expanded', 'false');

  // Type to trigger autocomplete
  await combobox.fill('test');
  await expect(combobox).toHaveAttribute('aria-expanded', 'true');

  // Listbox should appear
  const listbox = page.getByRole('listbox');
  await expect(listbox).toBeVisible();

  // Navigate with arrow keys
  await page.keyboard.press('ArrowDown');

  const firstOption = page.getByRole('option').first();
  await expect(firstOption).toHaveAttribute('aria-selected', 'true');
});

Accessibility Testing Checklist

Page Level

• Page has a unique, descriptive title
• Page language is declared (<html lang="en">)
• Heading hierarchy is logical (h1 → h2 → h3)
• Skip to main content link is provided
• Landmark regions are properly defined

Images

• All images have appropriate alt text
• Decorative images use alt="" or role="presentation"
• Complex images have extended descriptions
• Icons have accessible labels

Forms

• All form controls have labels
• Required fields are indicated
• Error messages are clear and accessible
• Field validation is announced
• Form can be completed with keyboard only

Interactive Elements

• All interactive elements are keyboard accessible
• Focus order is logical
• Focus indicators are visible
• Modals trap focus correctly
• ARIA roles are used correctly

Color and Contrast

• Color contrast meets WCAG AA (4.5:1 for text)
• Information not conveyed by color alone
• High contrast mode is supported

Dynamic Content

• ARIA live regions announce changes
• Loading states are announced
• Dynamic content updates are perceivable

Best Practices

1. Use semantic HTML -- <button> over <div role="button">.
2. Provide text alternatives -- Alt text, captions, transcripts.
3. Ensure keyboard access -- All functionality must work without mouse.
4. Test with real screen readers -- NVDA, JAWS, VoiceOver.
5. Use ARIA sparingly -- Only when HTML semantics are insufficient.
6. Maintain focus order -- Logical tab order matches visual order.
7. Announce state changes -- Use ARIA live regions for dynamic updates.
8. Test with zoom -- Content should be usable at 200% zoom.
9. Support high contrast -- Respect user color preferences.
10. Document accessibility features -- Help users discover a11y features.

Anti-Patterns to Avoid

1. Using role="button" on <div> -- Use native <button>.
2. Missing alt text on images -- Always provide alternative text.
3. Keyboard traps -- Users must be able to navigate away.
4. Invisible focus indicators -- outline: none without replacement.
5. ARIA overuse -- Don't reinvent native semantics.
6. Color-only information -- Use text labels or patterns too.
7. Auto-playing media -- Provide controls, allow user to pause.
8. Time limits without extension -- Allow users to extend time.
9. Inconsistent navigation -- Keep navigation predictable.
10. Relying on automated tests alone -- Manual testing is essential.

Tools and Resources

Automated Testing:

• axe-core (Playwright, Cypress integration)
• Lighthouse (Chrome DevTools)
• WAVE browser extension

Manual Testing:

• NVDA (Windows screen reader)
• JAWS (Windows screen reader)
• VoiceOver (macOS/iOS screen reader)
• Keyboard navigation
• Color contrast analyzers

Learning Resources:

• WCAG 2.1 Guidelines
• ARIA Authoring Practices Guide
• WebAIM articles and resources

Accessibility is not optional. Building inclusive experiences makes the web better for everyone.