react-animations（React animations 前端）

React Animations

Production-quality animations in React using Framer Motion (primary), React Spring (physics), GSAP (timelines), and CSS/Tailwind (simple cases).

Library Decision Table

Core Principles

Matt Perry (Framer Motion creator): "Animations should be declared, not imperatively managed. Describe the target state — the library handles the rest." Sarah Drasner: "Animation is not decoration — it's communication. Every motion should serve a purpose."

1. CSS for simple, JS for complex — if Tailwind transition works, use it; don't add Framer Motion for hover states
2. Only animate composited properties — transform and opacity; never width, height, top, left (causes reflow)
3. AnimatePresence wraps conditional renders — without it, exit animations are skipped
4. Variants for coordinated animations — define animation states as objects outside the component, not inline values
5. layoutId for shared element transitions — Framer Motion handles the interpolation between positions
6. useMotionValue for gesture-driven — don't use useState for values that drive animations
7. 60fps budget — keep animation logic out of render cycle; use transforms

Key Framer Motion Patterns

Basic Animate

<motion.div
  initial={{ opacity: 0 }}
  animate={{ opacity: 1 }}
  transition={{ duration: 0.3 }}
/>

Gesture States (whileHover, whileTap)

<motion.button
  whileHover={{ scale: 1.05 }}
  whileTap={{ scale: 0.95 }}
  transition={{ type: 'spring', stiffness: 400, damping: 17 }}
/>

Variants with Children Stagger

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} />
  ))}
</motion.ul>

AnimatePresence with Exit

The mode prop controls how entering/exiting elements interact:

• "sync" (default) — enter and exit happen simultaneously
• "wait" — exit completes before enter starts (good for page transitions)
• "popLayout" — exiting element is removed from layout flow immediately

<AnimatePresence mode="wait">
  {isVisible && (
    <motion.div
      key="modal"
      initial={{ opacity: 0, scale: 0.9 }}
      animate={{ opacity: 1, scale: 1 }}
      exit={{ opacity: 0, scale: 0.9 }}
    />
  )}
</AnimatePresence>

whileInView for Scroll-Triggered Animations

The simplest approach — no scroll hooks needed:

<motion.div
  initial={{ opacity: 0, y: 40 }}
  whileInView={{ opacity: 1, y: 0 }}
  viewport={{ once: true, margin: '-100px' }}
  transition={{ duration: 0.5 }}
/>

Use viewport.once: true so the animation doesn't replay on scroll back.

useScroll + useTransform for Parallax

const { scrollYProgress } = useScroll();
const y = useTransform(scrollYProgress, [0, 1], [0, -200]);

<motion.div style={{ y }} />

layoutId Shared Element

// In list view
<motion.div layoutId={`card-${id}`}>
  <Thumbnail />
</motion.div>

// In detail view
<motion.div layoutId={`card-${id}`}>
  <FullImage />
</motion.div>

Drag with Constraints

<motion.div
  drag
  dragConstraints={{ left: -100, right: 100, top: -50, bottom: 50 }}
  dragElastic={0.2}
  whileDrag={{ scale: 1.1 }}
/>

useAnimate — Imperative Animations (v11+)

Prefer useAnimate over useAnimation for programmatic sequences. It's scoped to a ref and works with any selector within that scope:

const [scope, animate] = useAnimate();

const handleClick = async () => {
  await animate(scope.current, { scale: 1.2 }, { duration: 0.2 });
  await animate(scope.current, { scale: 1 }, { duration: 0.1 });
};

<div ref={scope}>
  <button onClick={handleClick}>Click me</button>
</div>

MotionConfig — Global Animation Settings

Wrap your app (or a subtree) to set defaults like reduced motion or spring presets:

<MotionConfig reducedMotion="user">
  <App />
</MotionConfig>

reducedMotion="user" automatically disables animations for users with OS-level "reduce motion" preferences. This is the easiest way to handle accessibility at scale.

LazyMotion — Bundle Size Optimization

For production apps, replace motion with LazyMotion + m to code-split the animation engine:

import { LazyMotion, domAnimation, m } from 'framer-motion';

<LazyMotion features={domAnimation}>
  <m.div animate={{ opacity: 1 }} />
</LazyMotion>

Use domMax instead of domAnimation if you need drag or layout animations.

Game UI Patterns

Health Bar Smooth Tweening

const motionWidth = useMotionValue(current / max);
const springWidth = useSpring(motionWidth, { stiffness: 200, damping: 30 });

useEffect(() => {
  motionWidth.set(Math.max(0, Math.min(1, current / max)));
}, [current, max]);

<motion.div style={{ scaleX: springWidth, transformOrigin: 'left' }} />

Damage Numbers Floating Up

<motion.span
  initial={{ opacity: 1, y: 0 }}
  animate={{ opacity: 0, y: -60 }}
  transition={{ duration: 0.8, ease: 'easeOut' }}
  onAnimationComplete={onComplete}
>
  -{damage}
</motion.span>

Card Flip (rotateY)

<motion.div animate={{ rotateY: isFlipped ? 180 : 0 }} style={{ perspective: 1000 }}>
  <div style={{ backfaceVisibility: 'hidden' }}>{front}</div>
  <div style={{ backfaceVisibility: 'hidden', rotateY: 180 }}>{back}</div>
</motion.div>

Screen Shake (useAnimate)

const [scope, animate] = useAnimate();

const shake = async () => {
  await animate(scope.current, { x: [0, -10, 10, -10, 10, 0] }, { duration: 0.4 });
};

<div ref={scope}>{children}</div>

Menu Slide-In / Slide-Out

<AnimatePresence>
  {isOpen && (
    <motion.nav
      initial={{ x: -300 }}
      animate={{ x: 0 }}
      exit={{ x: -300 }}
      transition={{ type: 'spring', stiffness: 300, damping: 30 }}
    />
  )}
</AnimatePresence>

Inventory Item Drop (Spring Physics)

<motion.div
  initial={{ y: -200, opacity: 0 }}
  animate={{ y: 0, opacity: 1 }}
  transition={{ type: 'spring', stiffness: 400, damping: 15 }}
/>

Accessibility

Always respect the user's motion preferences. Two approaches:

1. MotionConfig (recommended for apps) — wraps your entire component tree:

<MotionConfig reducedMotion="user">
  <App />
</MotionConfig>

2. useReducedMotion hook — for component-level control:

const shouldReduceMotion = useReducedMotion();

<motion.div
  animate={{ opacity: 1, y: shouldReduceMotion ? 0 : -20 }}
/>

Performance

• Animate only transform and opacity — GPU-composited, no layout/paint triggered
• will-change: transform for elements that always animate (promotes to own layer)
• Use motion.create(Component) to animate custom components without wrapper divs
• layout prop triggers automatic layout animations — expensive on large DOM trees; scope to smallest possible subtree
• Prefer useMotionValue over useState for animation-driving values — motion values don't trigger re-renders
• LazyMotion with domAnimation saves ~15kb gzip vs the full bundle

Setup

bun add framer-motion

Zero-config — no providers required. Import and use motion.div directly.

For global accessibility handling, wrap your app root:

import { MotionConfig } from 'framer-motion';

<MotionConfig reducedMotion="user">
  <App />
</MotionConfig>

Boilerplate

boilerplate/motion-components.tsx — ready-to-use components: FadeIn, SlideIn, ScaleIn, StaggerList, FloatingNumber, HealthBar, AnimatedCard

templates/animation-variants.ts — reusable variant objects and spring transition presets

Cross-References

• vercel-react-best-practices — React performance patterns
• ui-ux-game — game HUD and UI patterns
• frontend-design — component design and Tailwind patterns

Pitfalls & Anti-Patterns

• Animating layout-triggering properties (width, height, top, left) — use scaleX/scaleY or the layout prop instead
• Forgetting AnimatePresence when using exit prop — exit animations silently skip without the wrapper
• Creating motion values in render — use useMotionValue hook; creating in render causes memory leaks
• Using CSS transition AND Framer Motion on same element — they conflict; pick one
• Over-animating — every interaction animated is sensory overload; animate to communicate, not to decorate
• Animating on mount without initial — component flashes before animating; always set initial
• Using useAnimation — deprecated; use useAnimate for imperative animations instead
• Large layout animations — layout prop on deeply nested trees causes expensive recalculations; scope to smallest possible subtree
• Skipping accessibility — always use MotionConfig reducedMotion="user" or useReducedMotion

Sources

• Framer Motion documentation — https://motion.dev
• Matt Perry — Framer Motion creator, API design talks
• Sarah Drasner — "SVG Animations", animation design patterns
• GSAP documentation — https://gsap.com