Emil Kowalski Animation Best Practices

Comprehensive animation guide for web interfaces based on Emil Kowalski's teachings, open-source libraries (Sonner, Vaul), and his animations.dev course. Contains 43 rules across 7 categories, prioritized by impact.

When to Apply

Reference these guidelines when:

• Adding animations to React components
• Choosing easing curves or timing values
• Implementing gesture-based interactions (swipe, drag)
• Building toast notifications or drawer components
• Optimizing animation performance
• Ensuring animation accessibility

Rule Categories by Priority

ease-

timing-

props-

transform-

interact-

strategy-

polish-

Quick Reference

1. Easing Selection (CRITICAL)

• ease-out-default

  - Use ease-out as your default easing

• ease-custom-curves

  - Use custom cubic-bezier over built-in CSS

• ease-in-out-onscreen

  - Use ease-in-out for on-screen movement

• ease-spring-natural

  - Use spring animations for natural motion

• ease-ios-drawer

  - Use iOS-style easing for drawer components

• ease-context-matters

  - Match easing to animation context

2. Timing & Duration (CRITICAL)

• timing-300ms-max

  - Keep UI animations under 300ms

• timing-faster-better

  - Faster animations improve perceived performance

• timing-asymmetric

  - Use asymmetric timing for press and release

• timing-tooltip-delay

  - Delay initial tooltips, instant subsequent ones

• timing-drawer-500ms

  - Use 500ms duration for drawer animations

3. Property Selection (HIGH)

• props-transform-opacity

  - Animate only transform and opacity

• props-hardware-accelerated

  - Use hardware-accelerated animations when main thread is busy

• props-will-change

  - Use will-change to prevent 1px shift

• props-avoid-css-variables

  - Avoid CSS variables for drag animations

• props-clip-path-performant

  - Use clip-path for layout-free reveals

4. Transform Techniques (HIGH)

• transform-scale-097

  - Scale buttons to 0.97 on press

• transform-never-scale-zero

  - Never animate from scale(0)

• transform-percentage-translate

  - Use percentage values for translateY

• transform-origin-aware

  - Make animations origin-aware

• transform-scale-children

  - Scale transforms affect children

• transform-3d-preserve

  - Use preserve-3d for 3D transform effects

5. Interaction Patterns (MEDIUM-HIGH)

• interact-interruptible

  - Make animations interruptible

• interact-momentum-dismiss

  - Use momentum-based dismissal

• interact-damping

  - Damp drag at boundaries

• interact-scroll-drag-conflict

  - Resolve scroll and drag conflicts

• interact-snap-points

  - Implement velocity-aware snap points

• interact-friction-upward

  - Allow upward drag with friction

• interact-pointer-capture

  - Use pointer capture for drag operations

6. Strategic Animation (MEDIUM)

• strategy-keyboard-no-animate

  - Never animate keyboard-initiated actions

• strategy-frequency-matters

  - Consider interaction frequency before animating

• strategy-purpose-required

  - Every animation must have a purpose

• strategy-feedback-immediate

  - Provide immediate feedback on all actions

• strategy-marketing-exception

  - Marketing sites are the exception

7. Accessibility & Polish (MEDIUM)

• polish-reduced-motion

  - Respect prefers-reduced-motion

• polish-opacity-fallback

  - Use opacity as reduced motion fallback

• polish-framer-hook

  - Use useReducedMotion hook in Framer Motion

• polish-dont-remove-all

  - Don't remove all animation for reduced motion

• polish-blur-bridge

  - Use blur to bridge animation states

• polish-clip-path-tabs

  - Use clip-path for tab transitions

• polish-toast-stacking

  - Implement toast stacking with scale and offset

• polish-scroll-reveal

  - Trigger scroll animations at appropriate threshold

• polish-hover-gap-fill

  - Fill gaps between hoverable elements

• polish-stagger-children

  - Stagger child animations for orchestration

Key Values Reference

cubic-bezier(0.32, 0.72, 0, 1)

scale(0.97)

scale(0.95)

200ms ease-out

300ms

500ms

0.11 px/ms

100px

14px

Reference Files