animate

name	animate
description	Animation patterns and best practices for Next.js/React applications. Use this skill when implementing animations, transitions, hover effects, page transitions, modals, or any motion in React components. Based on Emil Kowalski's "Animations on the Web" course.

Next.js Animations

Overview

This skill provides comprehensive guidance for implementing smooth, performant, and accessible animations in Next.js and React applications. It covers CSS animations, Framer Motion, easing principles, and accessibility considerations.

Quick Reference

Easing Cheat Sheet

Animation Type	Easing	Duration
Element entering	ease-out	200-300ms
Element moving on screen	ease-in-out	200-300ms
Element exiting	ease-in	150-200ms
Hover effects	ease	150ms
Opacity only	linear	varies

CSS Custom Properties (Recommended)

:root {
  --ease-out-quint: cubic-bezier(.23, 1, .32, 1);
  --ease-in-out-cubic: cubic-bezier(.645, .045, .355, 1);
  --ease-out-cubic: cubic-bezier(.33, 1, .68, 1);
}

Common Animation Patterns

1. Hover Lift Effect

.card {
  transition: transform 200ms var(--ease-out-quint),
              box-shadow 200ms var(--ease-out-quint);
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.15);
}

2. Button Press

.button {
  transition: transform 100ms ease-out;
}
.button:active {
  transform: scale(0.97);
}

3. Fade In on Mount (Framer Motion)

<motion.div
  initial={{ opacity: 0, y: 20 }}
  animate={{ opacity: 1, y: 0 }}
  transition={{ duration: 0.3, ease: [.23, 1, .32, 1] }}
>
  Content
</motion.div>

4. Modal with Exit Animation

<AnimatePresence>
  {isOpen && (
    <motion.div
      initial={{ opacity: 0, scale: 0.95 }}
      animate={{ opacity: 1, scale: 1 }}
      exit={{ opacity: 0, scale: 0.95 }}
      transition={{ duration: 0.2, ease: "easeOut" }}
    >
      {children}
    </motion.div>
  )}
</AnimatePresence>

5. Tab Indicator (Shared Layout)

{tabs.map(tab => (
  <button key={tab} onClick={() => setActive(tab)} className="relative px-4 py-2">
    {tab}
    {active === tab && (
      <motion.div
        layoutId="tab-indicator"
        className="absolute inset-0 bg-blue-500 rounded -z-10"
        transition={{ type: "spring", stiffness: 400, damping: 30 }}
      />
    )}
  </button>
))}

6. Staggered List Animation

const container = {
  hidden: { opacity: 0 },
  visible: {
    opacity: 1,
    transition: { staggerChildren: 0.1 }
  }
}

const item = {
  hidden: { opacity: 0, y: 20 },
  visible: { opacity: 1, y: 0 }
}

<motion.ul variants={container} initial="hidden" animate="visible">
  {items.map(i => <motion.li key={i} variants={item}>{i}</motion.li>)}
</motion.ul>

Golden Rules

1. Exits faster than enters: Exit animations should be ~75% of enter duration
2. Only animate transform and opacity: These are GPU-accelerated
3. 200-300ms is the sweet spot: Most animations should be in this range
4. Always respect prefers-reduced-motion: See accessibility section in references
5. Use springs for interruptible animations: Better UX when users interrupt

Examples

Complete working examples from the course are in the examples/ directory:

Example	Description	Key Techniques
card-hover.tsx	Slide-up description on hover	CSS transitions, transform, opacity
toast-stacking.tsx	Animated toast notifications	CSS custom properties, data-* triggers
text-reveal.tsx	Staggered letter animation	@keyframes, animation-delay, calc()
shared-layout.tsx	Element position/size morph	Framer Motion layoutId
animate-height.tsx	Smooth height changes	useMeasure, animate height
multi-step-flow.tsx	Directional step wizard	AnimatePresence, custom variants
feedback-popover.tsx	Button-to-popover expansion	Nested layoutId, form states
app-store-card.tsx	iOS-style card expansion	Multiple layoutId elements

To use an example, read it with: Read examples/<name>.tsx

References

For detailed documentation, read the reference files:

• references/easing-and-timing.md - Easing functions, timing guidelines, spring configuration
• references/css-animations.md - Transforms, transitions, keyframes, clip-path
• references/framer-motion.md - Motion components, AnimatePresence, variants, layout animations, hooks
• references/performance-accessibility.md - 60fps optimization, prefers-reduced-motion, accessibility

When to Use What

Scenario	Recommended Approach
Simple hover effects	CSS transitions
Enter/exit animations	Framer Motion + AnimatePresence
Layout changes	Framer Motion layout prop
Shared element transitions	Framer Motion layoutId
Scroll-linked animations	Framer Motion useScroll
Complex orchestrated animations	Framer Motion variants
Drag interactions	Framer Motion drag gestures
Performance-critical	CSS-only with transforms

Dependencies

For Framer Motion examples, install:

pnpm add framer-motion react-use-measure usehooks-ts