Accessibility Auditor

Audits web applications for accessibility compliance (WCAG 2.1 Level AA) and suggests improvements.

When to Use

• Building or reviewing UI components
• User requests accessibility improvements
• Preparing for accessibility audit
• User mentions "accessibility", "a11y", "WCAG", "screen reader", or "keyboard navigation"

Instructions

1. Semantic HTML Check

Use proper HTML elements:

<!-- Bad -->
<div onclick="submit()">Submit</div>

<!-- Good -->
<button onclick="submit()">Submit</button>

Semantic structure:

• <header>

  ,

  <nav>

  ,

  <main>

  ,

  <footer>

• <article>

  ,

  <section>

  ,

  <aside>

• <h1>

  through

  <h6>

  in proper hierarchy

• <button>

  for actions,

  <a>

  for navigation

2. ARIA Attributes

When to use ARIA:

• Custom widgets (tabs, accordions, modals)
• Dynamic content updates
• Complex interactions
• When semantic HTML isn't sufficient

Common ARIA attributes:

<!-- Landmark roles -->
<nav role="navigation" aria-label="Main">

<!-- Widget roles -->
<div role="button" tabindex="0" aria-pressed="false">

<!-- Live regions -->
<div role="alert" aria-live="assertive">Error occurred</div>

<!-- Labels and descriptions -->
<button aria-label="Close dialog">×</button>
<input aria-describedby="password-help" />

First rule of ARIA: Don't use ARIA if semantic HTML works

3. Keyboard Navigation

All interactive elements must be keyboard accessible:

// Add keyboard support to custom elements
<div
  role="button"
  tabindex="0"
  onClick={handleClick}
  onKeyDown={(e) => {
    if (e.key === 'Enter' || e.key === ' ') {
      handleClick();
    }
  }}
>
  Click me
</div>

Tab order:

• Use

  tabindex="0"

  for custom interactive elements
• Avoid

  tabindex > 0

  (creates confusing tab order)
• Use

  tabindex="-1"

  for programmatic focus only

Focus management:

• Visible focus indicators
• Trap focus in modals
• Return focus when closing dialogs
• Skip links for main content

4. Alt Text and Images

Informative images:

<img src="chart.png" alt="Sales increased 25% in Q3" />

Decorative images:

<img src="decoration.png" alt="" />
<!-- or -->
<img src="decoration.png" role="presentation" />

Complex images:

<figure>
  <img src="complex-chart.png" alt="Quarterly sales chart" />
  <figcaption>
    Detailed description of the chart data...
  </figcaption>
</figure>

5. Color and Contrast

Contrast ratios (WCAG AA):

• Normal text: 4.5:1 minimum
• Large text (18pt+): 3:1 minimum
• UI components: 3:1 minimum

Don't rely on color alone:

<!-- Bad: Color only -->
<span style="color: red;">Error</span>

<!-- Good: Icon + color -->
<span style="color: red;">
  <svg aria-hidden="true"><!-- error icon --></svg>
  <span class="sr-only">Error: </span>
  Invalid input
</span>

6. Forms and Labels

Every input needs a label:

<!-- Explicit label -->
<label for="email">Email</label>
<input id="email" type="email" />

<!-- Implicit label -->
<label>
  Email
  <input type="email" />
</label>

<!-- aria-label for icon buttons -->
<button aria-label="Search">
  <svg><!-- search icon --></svg>
</button>

Error messages:

<input
  id="password"
  aria-invalid="true"
  aria-describedby="password-error"
/>
<div id="password-error" role="alert">
  Password must be at least 8 characters
</div>

7. Headings and Document Structure

Proper heading hierarchy:

<h1>Page Title</h1>
  <h2>Section 1</h2>
    <h3>Subsection 1.1</h3>
    <h3>Subsection 1.2</h3>
  <h2>Section 2</h2>

Don't skip levels: h1 → h2 → h3 (not h1 → h3)

8. Dynamic Content

Announce updates to screen readers:

<!-- Polite: wait for user to pause -->
<div role="status" aria-live="polite">
  5 new messages
</div>

<!-- Assertive: interrupt immediately -->
<div role="alert" aria-live="assertive">
  Your session will expire in 1 minute
</div>

Loading states:

<button aria-busy="true" aria-label="Loading...">
  <span aria-hidden="true">Loading</span>
</button>

9. Screen Reader Testing

Screen reader only text:

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

Hide decorative elements:

<svg aria-hidden="true"><!-- icon --></svg>

10. Common Issues to Check

Missing:

• Alt text on images
• Labels on form inputs
• Proper heading hierarchy
• Keyboard focus indicators
• ARIA labels on icon buttons

Improper:

• Low contrast text
• Non-semantic markup (divs as buttons)
• Missing focus management in modals
• Keyboard traps
• Auto-playing media

Testing:

• Keyboard only navigation
• Screen reader (NVDA, JAWS, VoiceOver)
• Color blindness simulation
• Zoom to 200%
• Automated tools (axe, Lighthouse)

11. Automated Testing

Tools:

# Lighthouse
npx lighthouse https://example.com --only-categories=accessibility

# axe-core
npm install --save-dev @axe-core/cli
npx axe https://example.com

# pa11y
npm install --save-dev pa11y
npx pa11y https://example.com

In tests:

import { axe } from 'jest-axe';

test('should have no accessibility violations', async () => {
  const { container } = render(<MyComponent />);
  const results = await axe(container);
  expect(results).toHaveNoViolations();
});

12. WCAG 2.1 Level AA Checklist

Perceivable:

• Text alternatives for non-text content
• Captions for audio/video
• Content adaptable (semantic markup)
• Sufficient color contrast

Operable:

• Keyboard accessible
• No keyboard traps
• Adequate time limits (adjustable)
• No seizure-inducing flashing
• Skip navigation links
• Descriptive page titles
• Focus order makes sense
• Link purpose clear from context

Understandable:

• Language of page specified (

  <html lang="en">

  )
• Predictable navigation
• Input assistance (labels, instructions, error messages)

Robust:

• Valid HTML
• Name, role, value for custom widgets
• Compatible with assistive technologies

Best Practices

• Build accessibility in from start
• Test with real assistive technologies
• Use semantic HTML first, ARIA second
• Maintain logical document structure
• Provide multiple ways to access content
• Test keyboard navigation thoroughly
• Don't disable zoom
• Use landmarks and headings

Supporting Files

• reference/wcag-checklist.md

  : Full WCAG 2.1 AA checklist

• reference/aria-patterns.md

  : Common ARIA widget patterns