auto-animate

# AutoAnimate

**Status**: Production Ready ✅
**Last Updated**: 2025-11-07
**Dependencies**: None (works with any React setup)
**Latest Versions**: @formkit/auto-animate@0.9.0

---

## Quick Start (2 Minutes)

### 1. Install AutoAnimate

```bash
bun add @formkit/auto-animate
```

**Why this matters:**
- Only 3.28 KB gzipped (vs 22 KB for Motion)
- Zero dependencies
- Framework-agnostic (React, Vue, Svelte, vanilla JS)

### 2. Add to Your Component

```tsx
import { useAutoAnimate } from "@formkit/auto-animate/react";

export function MyList() {
  const [parent] = useAutoAnimate(); // 1. Get ref

  return (
    <ul ref={parent}> {/* 2. Attach to parent */}
      {items.map(item => (
        <li key={item.id}>{item.text}</li> {/* 3. That's it! */}
      ))}
    </ul>
  );
}
```

**CRITICAL:**
- ✅ Always use unique, stable keys for list items
- ✅ Parent element must always be rendered (not conditional)
- ✅ AutoAnimate respects `prefers-reduced-motion` automatically
- ✅ Works on add, remove, AND reorder operations

### 3. Use in Production (SSR-Safe)

For Cloudflare Workers or Next.js:

```tsx
// Use client-only import to prevent SSR errors
import { useState, useEffect } from "react";

export function useAutoAnimateSafe<T extends HTMLElement>() {
  const [parent, setParent] = useState<T | null>(null);

  useEffect(() => {
    if (typeof window !== "undefined" && parent) {
      import("@formkit/auto-animate").then(({ default: autoAnimate }) => {
        autoAnimate(parent);
      });
    }
  }, [parent]);

  return [parent, setParent] as const;
}
```

---

## Known Issues Prevention

This skill prevents **10+** documented issues:

### Issue #1: SSR/Next.js Import Errors
**Error**: "Can't import the named export 'useEffect' from non EcmaScript module"
**Source**: https://github.com/formkit/auto-animate/issues/55
**Why It Happens**: AutoAnimate uses DOM APIs not available on server
**Prevention**: Use dynamic imports (see `templates/vite-ssr-safe.tsx`)

### Issue #2: Conditional Parent Rendering
**Error**: Animations don't work when parent is conditional
**Source**: https://github.com/formkit/auto-animate/issues/8
**Why It Happens**: Ref can't attach to non-existent element
**Prevention**:
```tsx
// ❌ Wrong
{showList && <ul ref={parent}>...</ul>}

// ✅ Correct
<ul ref={parent}>{showList && items.map(...)}</ul>
```

### Issue #3: Missing Unique Keys
**Error**: Items don't animate correctly or flash
**Source**: Official docs
**Why It Happens**: React can't track which items changed
**Prevention**: Always use unique, stable keys (`key={item.id}`)

### Issue #4: Flexbox Width Issues
**Error**: Elements snap to width instead of animating smoothly
**Source**: Official docs
**Why It Happens**: `flex-grow: 1` waits for surrounding content
**Prevention**: Use explicit width instead of flex-grow for animated elements

### Issue #5: Table Row Display Issues
**Error**: Table structure breaks when removing rows
**Source**: https://github.com/formkit/auto-animate/issues/7
**Why It Happens**: Display: table-row conflicts with animations
**Prevention**: Apply to `<tbody>` instead of individual rows, or use div-based layouts

### Issue #6: Jest Testing Errors
**Error**: "Cannot find module '@formkit/auto-animate/react'"
**Source**: https://github.com/formkit/auto-animate/issues/29
**Why It Happens**: Jest doesn't resolve ESM exports correctly
**Prevention**: Configure `moduleNameMapper` in jest.config.js

### Issue #7: esbuild Compatibility
**Error**: "Path '.' not exported by package"
**Source**: https://github.com/formkit/auto-animate/issues/36
**Why It Happens**: ESM/CommonJS condition mismatch
**Prevention**: Configure esbuild to handle ESM modules properly

### Issue #8: CSS Position Side Effects
**Error**: Layout breaks after adding AutoAnimate
**Source**: Official docs
**Why It Happens**: Parent automatically gets `position: relative`
**Prevention**: Account for position change in CSS or set explicitly

### Issue #9: Vue/Nuxt Registration Errors
**Error**: "Failed to resolve directive: auto-animate"
**Source**: https://github.com/formkit/auto-animate/issues/43
**Why It Happens**: Plugin not registered correctly
**Prevention**: Proper plugin setup in Vue/Nuxt config (see references/)

### Issue #10: Angular ESM Issues
**Error**: Build fails with "ESM-only package"
**Source**: https://github.com/formkit/auto-animate/issues/72
**Why It Happens**: CommonJS build environment
**Prevention**: Configure ng-packagr for Angular Package Format

---

## When to Use AutoAnimate vs Motion

### Use AutoAnimate When:
- ✅ Simple list transitions (add/remove/sort)
- ✅ Accordion expand/collapse
- ✅ Toast notifications fade in/out
- ✅ Form validation messages appear/disappear
- ✅ Zero configuration preferred
- ✅ Small bundle size critical (3.28 KB)
- ✅ Applying to existing/3rd-party code
- ✅ "Good enough" animations acceptable

### Use Motion When:
- ✅ Complex choreographed animations
- ✅ Gesture controls (drag, swipe, hover)
- ✅ Scroll-based animations
- ✅ Spring physics animations
- ✅ SVG path animations
- ✅ Keyframe control needed
- ✅ Animation variants/orchestration
- ✅ Custom easing curves

**Rule of Thumb**: Use AutoAnimate for 90% of cases, Motion for hero/interactive animations.

---

## Critical Rules

### Always Do

✅ **Use unique, stable keys** - `key={item.id}` not `key={index}`
✅ **Keep parent in DOM** - Parent ref element always rendered
✅ **Client-only for SSR** - Dynamic import for server environments
✅ **Respect accessibility** - Keep `disrespectUserMotionPreference: false`
✅ **Test with motion disabled** - Verify UI works without animations
✅ **Use explicit width** - Avoid flex-grow on animated elements
✅ **Apply to tbody for tables** - Not individual rows

### Never Do

❌ **Conditional parent** - `{show && <ul ref={parent}>}`
❌ **Index as key** - `key={index}` breaks animations
❌ **Ignore SSR** - Will break in Cloudflare Workers/Next.js
❌ **Force animations** - `disrespectUserMotionPreference: true` break