accessibility-implementation

# Accessibility Implementation

Technical implementation of WCAG guidelines, ARIA patterns, and assistive technology support.

## Core Expertise

- **WCAG Compliance**: Implementing WCAG 2.1/2.2 success criteria in code
- **ARIA Patterns**: Correct usage of roles, states, and properties
- **Keyboard Navigation**: Focus management, key handlers, logical tab order
- **Screen Readers**: Content structure, announcements, live regions
- **Testing**: Automated and manual accessibility testing

## WCAG Quick Reference

### Level A (Must Have)

| Criterion | Implementation |
|-----------|----------------|
| 1.1.1 Non-text Content | `alt` for images, labels for inputs |
| 1.3.1 Info and Relationships | Semantic HTML, ARIA relationships |
| 2.1.1 Keyboard | All interactive elements keyboard accessible |
| 2.4.1 Bypass Blocks | Skip links, landmarks |
| 4.1.2 Name, Role, Value | ARIA labels, roles for custom widgets |

### Level AA (Should Have)

| Criterion | Implementation |
|-----------|----------------|
| 1.4.3 Contrast (Minimum) | 4.5:1 text, 3:1 large text |
| 1.4.11 Non-text Contrast | 3:1 for UI components |
| 2.4.6 Headings and Labels | Descriptive, hierarchical headings |
| 2.4.7 Focus Visible | Visible focus indicator (2px+ outline) |

## ARIA Patterns

### Buttons and Links

```html
<!-- Custom button -->
<div role="button" tabindex="0"
     aria-pressed="false"
     onkeydown="handleKeyDown(event)">
  Toggle Feature
</div>

<!-- Icon button (needs accessible name) -->
<button aria-label="Close dialog">
  <svg aria-hidden="true">...</svg>
</button>

<!-- Link vs button -->
<!-- Use link for navigation, button for actions -->
<a href="/page">Go to page</a>
<button type="button">Submit form</button>
```

### Form Controls

```html
<!-- Input with label -->
<label for="email">Email address</label>
<input id="email" type="email"
       aria-describedby="email-hint email-error"
       aria-invalid="true"
       required>
<div id="email-hint">We'll never share your email