PixelPilot uiux-infinite-scroll.instructions.md

UI/UX Infinite Scroll

Load more content as user scrolls with Intersection Observer. Accessible, performant, with graceful fallbacks.

---

OVERVIEW

This skill covers:

1. Intersection Observer implementation
2. Loading skeleton during fetch
3. "End of content" message
4. Manual "Load more" button fallback
5. Error handling and retry
6. Accessibility considerations

---

HTML STRUCTURE

<div class="feed" id="feed" role="feed" aria-busy="false">
  <!-- Content items -->
  <article class="feed__item">...</article>
  <article class="feed__item">...</article>
  <article class="feed__item">...</article>
  
  <!-- Sentinel element for intersection observer -->
  <div class="feed__sentinel" id="feed-sentinel" aria-hidden="true"></div>
  
  <!-- Loading state -->
  <div class="feed__loading" id="feed-loading" hidden>
    <div class="skeleton skeleton--card"></div>
    <div class="skeleton skeleton--card"></div>
    <div class="skeleton skeleton--card"></div>
  </div>
  
  <!-- End of content -->
  <div class="feed__end" id="feed-end" hidden>
    <p>You've reached the end!</p>
  </div>
  
  <!-- Error state -->
  <div class="feed__error" id="feed-error" hidden>
    <p>Failed to load more content.</p>
    <button class="btn btn--secondary" id="retry-btn">Try Again</button>
  </div>
  
  <!-- Manual load more (fallback) -->
  <button class="btn btn--secondary feed__load-more" id="load-more-btn" hidden>
    Load More
  </button>
</div>

<!-- Screen reader announcements -->
<div id="feed-status" role="status" aria-live="polite" class="sr-only"></div>

---

CSS STYLES

.feed {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.feed__item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
}

.feed__sentinel {
  height: 1px;
  width: 100%;
}

.feed__loading {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.feed__end {
  text-align: center;
  padding: var(--space-8) var(--space-4);
  color: var(--muted);
}

.feed__end p {
  font-size: var(--text-sm);
}

.feed__error {
  text-align: center;
  padding: var(--space-6);
  background: var(--color-error-soft);
  border-radius: var(--radius-lg);
}

.feed__error p {
  color: var(--color-error);
  margin-bottom: var(--space-4);
}

.feed__load-more {
  align-self: center;
  margin-top: var(--space-4);
}

/* Skeleton loading */
.skeleton--card {
  height: 200px;
  background: var(--surface);
  border-radius: var(--radius-lg);
  position: relative;
  overflow: hidden;
}

.skeleton--card::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.3),
    transparent
  );
  transform: translateX(-100%);
  animation: shimmer 1.5s infinite;
}

@keyframes shimmer {
  100% {
    transform: translateX(100%);
  }
}

@media (prefers-reduced-motion: reduce) {
  .skeleton--card::after {
    animation: none;
    transform: none;
    background: rgba(255, 255, 255, 0.1);
  }
}