Come usare
- Copia il comando e controlla il pacchetto prima di installarlo nel tuo ambiente agente.
- Controlla strumenti, credenziali e ambienti richiesti nel documento originale.
- Descrivi input e risultato desiderato; confronta l’output con le fonti.
npx skills add https://github.com/victorzhuk/skills --skill z-accessibilityPrima di iniziare
- L’installazione non include abbonamenti, quote API o accesso ai file.
- Stelle e installazioni indicano attività, non un test indipendente di qualità o sicurezza.
Documento Skill originale
Contenuto dal repository con titoli, esempi, codice, tabelle, link e immagini preservati.
Accessibility (a11y)
Target WCAG 2.2 AA unless the product contract specifies another version. Automated audits find a subset of issues; manual checks remain necessary.
Include the 2.2 additions: focus not obscured (2.4.11), alternatives to dragging (2.5.7), 24 CSS px target size with exceptions (2.5.8), consistent help (3.2.6), redundant entry (3.3.7), and accessible authentication (3.3.8).
WCAG Principles: POUR
| Principle | Description |
|---|---|
| Perceivable | Content can be perceived through different senses |
| Operable | Interface can be operated by all users |
| Understandable | Content and interface are understandable |
| Robust | Content works with assistive technologies |
Conformance levels
| Level | Requirement | Target |
|---|---|---|
| A | Minimum accessibility | Must pass |
| AA | Standard compliance | Must pass (legal requirement in many jurisdictions) |
| AAA | Enhanced accessibility | Optional — only when the product contract requires it |
Perceivable
Text alternatives (1.1)
Images require alt text:
html
<!-- ❌ Missing alt -->
<img src="chart.png">
<!-- ✅ Descriptive alt -->
<img src="chart.png" alt="Bar chart showing 40% increase in Q3 sales">
<!-- ✅ Decorative image (empty alt) -->
<img src="decorative-border.png" alt="" role="presentation">
<!-- ✅ Complex image with longer description -->
<figure>
<img src="infographic.png" alt="2024 market trends infographic"
aria-describedby="infographic-desc">
<figcaption id="infographic-desc">
<!-- Detailed description -->
</figcaption>
</figure>Icon buttons need accessible names:
html
<!-- ❌ No accessible name -->
<button><svg><!-- menu icon --></svg></button>
<!-- ✅ Using aria-label -->
<button aria-label="Open menu">
<svg aria-hidden="true"><!-- menu icon --></svg>
</button>
<!-- ✅ Using visually hidden text -->
<button>
<svg aria-hidden="true"><!-- menu icon --></svg>
<span class="visually-hidden">Open menu</span>
</button>Visually hidden class:
css
.visually-hidden {
position: absolute;
width: 1px;
height: 1px;
padding: 0;
margin: -1px;
overflow: hidden;
clip: rect(0, 0, 0, 0);
white-space: nowrap;
border: 0;
}Color contrast (1.4.3, 1.4.6)
| Text Size | AA minimum | AAA enhanced |
|---|---|---|
| Normal text (< 24 CSS px regular / < 18.67 CSS px bold) | 4.5:1 | 7:1 |
| Large text (≥ 18pt regular / ≥ 14pt bold) | 3:1 | 4.5:1 |
| UI components & graphics | 3:1 | 3:1 |
css
/* ❌ Low contrast (2.5:1) */
.low-contrast {
color: #999;
background: #fff;
}
/* ✅ Sufficient contrast (7:1) */
.high-contrast {
color: #333;
background: #fff;
}
/* ✅ Focus states need contrast too */
:focus-visible {
outline: 2px solid #005fcc;
outline-offset: 2px;
}Don't rely on color alone:
html
<!-- ❌ Only color indicates error -->
<input class="error-border">
<style>.error-border { border-color: red; }</style>
<!-- ✅ Color + icon + text -->
<div class="field-error">
<input aria-invalid="true" aria-describedby="email-error">
<span id="email-error" class="error-message">
<svg aria-hidden="true"><!-- error icon --></svg>
Please enter a valid email address
</span>
</div>Media alternatives (1.2)
html
<!-- Video with captions -->
<video controls>
<source src="video.mp4" type="video/mp4">
<track kind="captions" src="captions.vtt" srclang="en" label="English" default>
<track kind="descriptions" src="descriptions.vtt" srclang="en" label="Descriptions">
</video>
<!-- Audio with transcript -->
<audio controls>
<source src="podcast.mp3" type="audio/mp3">
</audio>
<details>
<summary>Transcript</summary>
<p>Full transcript text...</p>
</details>Operable
Keyboard accessible (2.1)
Use native controls first. A native button already translates Enter/Space into activation; adding another key handler can invoke the action twice.
html
<button type="button" id="action">Run action</button>Attach one click handler to the button. For custom widgets, implement the matching WAI-ARIA Authoring Practices keyboard pattern.
For modal dialogs, prefer native dialog.showModal() or the project's maintained primitive. Verify initial focus, background isolation, Escape behavior, focus restoration, and the case with no focusable child. A Tab handler alone is not a complete dialog implementation.
Focus visible (2.4.7)
css
/* ❌ Never remove focus outlines */
*:focus { outline: none; }
/* ✅ Use :focus-visible for keyboard-only focus */
:focus {
outline: none;
}
:focus-visible {
outline: 2px solid #005fcc;
outline-offset: 2px;
}
/* ✅ Or custom focus styles */
button:focus-visible {
box-shadow: 0 0 0 3px rgba(0, 95, 204, 0.5);
}Skip links (2.4.1)
html
<body>
<a href="#main-content" class="skip-link">Skip to main content</a>
<header><!-- navigation --></header>
<main id="main-content" tabindex="-1">
<!-- main content -->
</main>
</body>css
.skip-link {
position: absolute;
top: -40px;
left: 0;
background: #000;
color: #fff;
padding: 8px 16px;
z-index: 100;
}
.skip-link:focus {
top: 0;
}Timing (2.2)
javascript
// Allow users to extend time limits
function showSessionWarning() {
const modal = createModal({
title: 'Session Expiring',
content: 'Your session will expire in 2 minutes.',
actions: [
{ label: 'Extend session', action: extendSession },
{ label: 'Log out', action: logout }
],
timeout: 120000 // 2 minutes to respond
});
}Motion (2.3)
css
/* Respect reduced motion preference */
@media (prefers-reduced-motion: reduce) {
*,
*::before,
*::after {
animation-duration: 0.01ms !important;
animation-iteration-count: 1 !important;
transition-duration: 0.01ms !important;
scroll-behavior: auto !important;
}
}Understandable
Page language (3.1.1)
html
<!-- ❌ No language specified -->
<html>
<!-- ✅ Language specified -->
<html lang="en">
<!-- ✅ Language changes within page -->
<p>The French word for hello is <span lang="fr">bonjour</span>.</p>Consistent navigation (3.2.3)
html
<!-- Navigation should be consistent across pages -->
<nav aria-label="Main">
<ul>
<li><a href="/" aria-current="page">Home</a></li>
<li><a href="/products">Products</a></li>
<li><a href="/about">About</a></li>
</ul>
</nav>Form labels (3.3.2)
html
<!-- ❌ No label association -->
<input type="email" placeholder="Email">
<!-- ✅ Explicit label -->
<label for="email">Email address</label>
<input type="email" id="email" name="email"
autocomplete="email" required>
<!-- ✅ Implicit label -->
<label>
Email address
<input type="email" name="email" autocomplete="email" required>
</label>
<!-- ✅ With instructions -->
<label for="password">Password</label>
<input type="password" id="password"
aria-describedby="password-requirements">
<p id="password-requirements">
Must be at least 8 characters with one number.
</p>Error handling (3.3.1, 3.3.3)
html
<!-- Announce errors to screen readers -->
<form novalidate>
<div class="field" aria-live="polite">
<label for="email">Email</label>
<input type="email" id="email"
aria-invalid="true"
aria-describedby="email-error">
<p id="email-error" class="error" role="alert">
Please enter a valid email address (e.g., name@example.com)
</p>
</div>
</form>javascript
// Focus first error on submit
form.addEventListener('submit', (e) => {
const firstError = form.querySelector('[aria-invalid="true"]');
if (firstError) {
e.preventDefault();
firstError.focus();
// Announce error summary
const errorSummary = document.getElementById('error-summary');
errorSummary.textContent = `${errors.length} errors found. Please fix them and try again.`;
errorSummary.focus();
}
});Robust
Valid HTML
WCAG 2.2 removed 4.1.1 Parsing. Validate markup because broken structure can still violate other criteria; do not report 4.1.1 as a 2.2 failure.
html
<!-- ❌ Duplicate IDs -->
<div id="content">...</div>
<div id="content">...</div>
<!-- ❌ Invalid nesting -->
<a href="/"><button>Click</button></a>
<!-- ✅ Unique IDs -->
<div id="main-content">...</div>
<div id="sidebar-content">...</div>
<!-- ✅ Proper nesting -->
<a href="/" class="button-link">Click</a>ARIA usage (4.1.2)
Prefer native elements:
html
<!-- ❌ ARIA role on div -->
<div role="button" tabindex="0">Click me</div>
<!-- ✅ Native button -->
<button>Click me</button>
<!-- ❌ ARIA checkbox -->
<div role="checkbox" aria-checked="false">Option</div>
<!-- ✅ Native checkbox -->
<label><input type="checkbox"> Option</label>When ARIA is needed:
html
<!-- Custom tabs component -->
<div role="tablist" aria-label="Product information">
<button role="tab" id="tab-1" aria-selected="true"
aria-controls="panel-1">Description</button>
<button role="tab" id="tab-2" aria-selected="false"
aria-controls="panel-2" tabindex="-1">Reviews</button>
</div>
<div role="tabpanel" id="panel-1" aria-labelledby="tab-1">
<!-- Panel content -->
</div>
<div role="tabpanel" id="panel-2" aria-labelledby="tab-2" hidden>
<!-- Panel content -->
</div>Live regions (4.1.3)
html
<!-- Status updates -->
<div aria-live="polite" aria-atomic="true" class="status">
<!-- Content updates announced to screen readers -->
</div>
<!-- Urgent alerts -->
<div role="alert" aria-live="assertive">
<!-- Interrupts current announcement -->
</div>javascript
// Announce dynamic content changes
function showNotification(message, type = 'polite') {
const container = document.getElementById(`${type}-announcer`);
container.textContent = ''; // Clear first
requestAnimationFrame(() => {
container.textContent = message;
});
}Testing and triage
Load references/testing-triage.md for automated checks, manual screen-reader commands, impact-based issue triage, and external references.
