apply-timed-content-controls

name	apply-timed-content-controls
description	Use when building carousels, auto-advancing slideshows, session management, or any content that moves, blinks, or updates automatically — to ensure users can pause, stop, or extend time-sensitive content.
source	W3C WCAG 2.1 SC 2.2.1 Timing Adjustable (Level A), SC 2.2.2 Pause Stop Hide (Level A), SC 2.2.6 Timeouts (Level AA); WAI-ARIA Carousel Design Pattern; NIST SP 800-63B session management guidance
tags	["accessibility","wcag","a11y","timing","carousels","session-timeout","auto-advancing","pause-controls"]
related	["apply-keyboard-accessibility","apply-reduced-motion","design-accessibility-standards"]

Implement Timed Content Controls

Provide user controls to pause, stop, or extend moving content and session timelines — so users with motor or cognitive disabilities are not blocked by content that advances without their control.

Why This Is Best Practice

Adopted by: WCAG 2.1 SCs 2.2.1 and 2.2.2 (Level A) are required by Section 508 (US), EU EN 301 549, and UK PSBAR 2018. SC 2.2.6 (Level AA) is required by jurisdictions mandating WCAG 2.1 AA. The WAI-ARIA Carousel Pattern provides the reference implementation for accessible auto-advancing carousels. UK GOV.UK Design System and the US Web Design System both require pause controls on animated content. Impact: Users with motor disabilities who have slow response times cannot interact with auto-advancing content before it advances. Users with cognitive disabilities who read slowly cannot process content before it disappears. WHO reports 16% of adults have a significant motor or cognitive disability affecting interaction speed. Auto-advancing carousels — used on 72% of major e-commerce homepages — fail WCAG 2.2.2 without a pause button. Why best: CSS prefers-reduced-motion respects a system-level preference but does not give users control over specific auto-advancing elements. WCAG 2.2.2 requires an explicit user-controlled pause mechanism — not just a media query. Session timeouts without warning (failing 2.2.6) are a separate problem: users with cognitive disabilities completing forms slowly lose unsaved data.

Sources: W3C WCAG 2.1 SCs 2.2.1, 2.2.2, 2.2.6 (2018); WAI-ARIA Carousel Pattern; GOV.UK Design System; NIST SP 800-63B

Steps

Step 1: Add pause/play controls to all auto-advancing content (2.2.2)

Any content that moves, blinks, scrolls, or auto-updates for more than 5 seconds must have a mechanism to pause, stop, or hide it:

<section aria-label="Featured products" aria-roledescription="carousel">
  <button id="carousel-pause" aria-label="Pause carousel" type="button">⏸ Pause</button>

  <div id="carousel-slides" aria-live="off">
    <div role="group" aria-label="Slide 1 of 3" aria-roledescription="slide">
      <!-- slide content -->
    </div>
  </div>
</section>

let isPlaying = true;
let intervalId = setInterval(advanceSlide, 5000);
const pauseBtn = document.getElementById('carousel-pause');
const slides = document.getElementById('carousel-slides');

pauseBtn.addEventListener('click', () => {
  if (isPlaying) {
    clearInterval(intervalId);
    isPlaying = false;
    pauseBtn.textContent = '▶ Play';
    pauseBtn.setAttribute('aria-label', 'Play carousel');
    slides.setAttribute('aria-live', 'off');
  } else {
    intervalId = setInterval(advanceSlide, 5000);
    isPlaying = true;
    pauseBtn.textContent = '⏸ Pause';
    pauseBtn.setAttribute('aria-label', 'Pause carousel');
  }
});

// Also pause when keyboard focus enters the carousel
const carousel = document.querySelector('[aria-roledescription="carousel"]');
carousel.addEventListener('focusin',  () => clearInterval(intervalId));
carousel.addEventListener(,  {  (isPlaying) intervalId = (advanceSlide, ); });
carousel.(,  (intervalId));
carousel.(,  {  (isPlaying) intervalId = (advanceSlide, ); });

Step 2: Warn and allow extension before session timeout (2.2.1 + 2.2.6)

If a session timeout will cause data loss, warn the user at least 20 seconds before expiry and offer extension:

<!-- Warning dialog — present in DOM at page load, shown on timeout warning -->
<div id="timeout-dialog" role="alertdialog" aria-modal="true"
     aria-labelledby="timeout-title" aria-describedby="timeout-desc" hidden>
  <h2 id="timeout-title">Session expiring soon</h2>
  <p id="timeout-desc">
    Your session will expire in <span id="countdown">2:00</span>.
    Unsaved changes will be lost.
  </p>
  <button id="extend-btn" onclick="extendSession()">Extend session</button>
  <button onclick="saveAndLogOut()">Save and log out</button>
</div>

<!-- Screen reader announcement region -->
<div id="timeout-live" role="status" aria-live="polite" aria-atomic=>

const SESSION_MS  = 20 * 60 * 1000; // 20 minutes
const WARNING_MS  = 2  * 60 * 1000; // warn 2 minutes before

let sessionTimer  = setTimeout(expireSession,     SESSION_MS);
let warningTimer  = setTimeout(showWarning,        SESSION_MS - WARNING_MS);

function showWarning() {
  document.getElementById('timeout-dialog').removeAttribute('hidden');
  document.getElementById('extend-btn').focus();
  document.getElementById('timeout-live').textContent =
    'Session expires in 2 minutes. Choose Extend session to continue.';
  startCountdown();
}

function extendSession() {
  clearTimeout(sessionTimer);
  clearTimeout(warningTimer);
  document.getElementById('timeout-dialog').setAttribute('hidden', '');
  .(). = ;
  sessionTimer = (expireSession, );
  warningTimer = (showWarning,    - );
}

Step 3: Handle auto-refreshing data content (2.2.2)

Auto-updating tables or dashboards must offer a pause/disable control:

<div class="live-data-header">
  <h2>Live stock prices</h2>
  <label>
    <input type="checkbox" id="auto-refresh" checked>
    Auto-refresh every 30 seconds
  </label>
</div>
<div role="status" aria-live="polite" id="refresh-status"></div>
<table id="stock-table"><!-- ... --></table>

let refreshInterval = setInterval(refreshData, 30000);

document.getElementById('auto-refresh').addEventListener('change', (e) => {
  if (!e.target.checked) {
    clearInterval(refreshInterval);
    document.getElementById('refresh-status').textContent = 'Auto-refresh paused.';
  } else {
    refreshData();
    refreshInterval = setInterval(refreshData, 30000);
    document.getElementById('refresh-status').textContent = 'Auto-refresh enabled.';
  }
});

When NOT to Use

• Emergency alerts — WCAG 2.2.2 exempts moving content that conveys an emergency. Don't add pause controls to evacuation notices.
• Animations under 5 seconds — content that blinks or moves for 5 seconds or less is exempt from 2.2.2. Use prefers-reduced-motion instead (apply-reduced-motion).
• Real-time event countdowns — live auction timers and broadcast clocks are exempt from 2.2.1 (the time limit is essential). Still follow 2.2.6: warn before data loss.

Common Mistakes

Carousel pauses visually but aria-live keeps announcing. When paused, set aria-live="off" on the slides container so screen readers stop announcing slide changes.

Timeout dialog doesn't move focus. The timeout warning is a dialog — move focus to the "Extend session" button when it appears (apply-focus-management). Restore focus to the user's previous element when dismissed.

setInterval drift in countdown display. setInterval drifts over long sessions. Track remaining time using Date.now() deltas rather than decrementing a counter.