--- name: Animations description: Create performant web animations with proper accessibility and timing. metadata: {"clawdbot":{"emoji":"✨","requires":{},"os":["linux","darwin","win32"]}} --- ## GPU-Accelerated Properties Only these properties animate on the compositor thread (60fps): | Property | Use | |----------|-----| | `transform` | Move, rotate, scale (translateX, rotate, scale) | | `opacity` | Fade in/out | Everything else triggers layout or paint. Avoid animating: - `width`, `height`, `margin`, `padding` (layout thrashing) - `top`, `left`, `right`, `bottom` (use transform instead) - `border-width`, `font-size` (expensive reflows) ```css /* ❌ Triggers layout every frame */ .slide { left: 100px; transition: left 0.3s; } /* ✅ GPU accelerated */ .slide { transform: translateX(100px); transition: transform 0.3s; } ``` ## Reduced Motion ~5% of users experience vestibular disorders (dizziness, nausea from motion). ```css /* Only animate if user hasn't requested reduced motion */ @media (prefers-reduced-motion: no-preference) { .animated { animation: slide-in 0.5s ease-out; } } /* Or disable for those who requested it */ @media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; } } ``` Keep subtle fades and color changes even with reduced motion. Remove parallax, bouncing, infinite loops. ## Timing Functions | Easing | Use case | |--------|----------| | `ease-out` | Elements entering view (appears responsive) | | `ease-in` | Elements exiting view (accelerates away) | | `ease-in-out` | Elements moving within view | | `linear` | Only for spinners, progress bars, color cycling | ```css /* Custom bounce */ transition: transform 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55); /* Material Design standard */ transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1); ``` ## Duration Guidelines | Type | Duration | |------|----------| | Micro-interactions (hover, focus) | 100-200ms | | Transitions (modals, dropdowns) | 200-300ms | | Page transitions | 300-500ms | | Complex choreography | 500-1000ms max | Anything over 500ms feels sluggish. Shorter is usually better. ## CSS Transitions vs Animations **Transitions:** A to B state changes ```css .button { transform: scale(1); transition: transform 0.2s ease-out; } .button:hover { transform: scale(1.05); } ``` **Animations:** Multi-step, auto-play, looping ```css @keyframes fadeSlideIn { 0% { opacity: 0; transform: translateY(20px); } 100% { opacity: 1; transform: translateY(0); } } .card { animation: fadeSlideIn 0.5s ease-out forwards; } ``` Use transitions for hover/focus states. Use animations for on-load effects and sequences. ## will-change Only use as optimization when you have specific performance problems: ```css /* ✅ Apply before animation starts, remove after */ .card:hover { will-change: transform; } .card { will-change: auto; } /* ❌ Never apply globally */ * { will-change: transform, opacity; } /* Wastes GPU memory */ ``` ## Transition Property Specificity ```css /* ❌ Animates everything including unintended properties */ .card { transition: all 0.3s; } /* ✅ Only animates what you need */ .card { transition: transform 0.3s, box-shadow 0.3s; } ``` `all` can cause unexpected animations on color, background, border changes. ## React/Framework Traps **Exit animations require AnimatePresence:** ```jsx /* ❌ Exit animation never plays */ {isVisible && } /* ✅ Wrap conditional rendering */ {isVisible && } ``` **Stable keys for list animations:** ```jsx /* ❌ Index keys cause erratic animations */ {items.map((item, i) =>

{item}

)} /* ✅ Stable IDs */ {items.map(item =>

{item.text}

)} ``` **AutoAnimate parent must be unconditional:** ```jsx /* ❌ Ref can't attach to conditional element */ {showList &&

...} /* ✅ Parent always renders, children are conditional */

{showList && items.map(...)} ``` ## Library Selection | Library | Size | Best for | |---------|------|----------| | CSS only | 0kb | Hover states, simple transitions | | AutoAnimate | 3kb | Lists, accordions, toasts (90% of UI animations) | | Motion | 22kb | Gestures, physics, scroll animations, complex choreography | | GSAP | 60kb | Timelines, creative animation, scroll-triggered sequences | Start with CSS. Add AutoAnimate for list animations. Only add Motion/GSAP for complex needs. ## Common Mistakes - Animating `width`/`height` instead of `scale`—causes layout thrashing - Infinite animations without pause control—no way to stop - Same easing for enter and exit—use ease-out for enter, ease-in for exit - Ignoring prefers-reduced-motion—causes physical discomfort - Duration over 500ms—feels sluggish - `transition: all` catching unintended properties - Missing AnimatePresence for exit animations in React

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