auto-animate

AutoAnimate - Error Prevention Guide

Package: @formkit/auto-animate@0.9.0 (current) Frameworks: React, Vue, Solid, Svelte, Preact Last Updated: 2026-01-21

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SSR-Safe Pattern (Critical for Cloudflare Workers/Next.js)

// 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;
}

Why this matters: Prevents Issue #1 (SSR/Next.js import errors). AutoAnimate uses DOM APIs not available on server.

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Known Issues Prevention (15 Documented Errors)

This skill prevents 15 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:

React Pattern:

// ❌ Wrong
{showList && <ul ref={parent}>...</ul>}

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

Vue.js Pattern:

<!-- ❌ Wrong - parent conditional -->
<ul v-if="showList" ref="parent">
  <li v-for="item in items" :key="item.id">{{ item.text }}</li>
</ul>

<!-- ✅ Correct - children conditional -->
<ul ref="parent">
  <li v-if="showList" v-for="item in items" :key="item.id">
    {{ item.text }}
  </li>
</ul>

Source: React Issue #8, Vue Issue #193

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 and Shaking Issues

Error: Elements snap to width instead of animating smoothly, or container shakes on remove Source: Official docs, Issue #212 Why It Happens: flex-grow: 1 waits for surrounding content, causing timing issues Prevention: Use explicit width instead of flex-grow for animated elements

// ❌ Wrong - causes shaking
<ul ref={parent} style={{ display: 'flex' }}>
  {items.map(item => (
    <li key={item.id} style={{ flex: '1 1 auto' }}>{item.text}</li>
  ))}
</ul>

// ✅ Correct - fixed sizes
<ul ref={parent} style={{ display: 'flex', gap: '1rem' }}>
  {items.map(item => (
    <li
      key={item.id}
      style={{ minWidth: '200px', maxWidth: '200px' }}
    >
      {item.text}
    </li>
  ))}
</ul>

Maintainer Note: justin-schroeder confirmed fixed sizes are required for flex containers

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/)

Nuxt 3 Note: Requires v0.8.2+ (April 2024). Earlier versions have ESM import issues fixed by Daniel Roe. See Issue #199

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

Issue #11: React 19 StrictMode Double-Call Bug

Error: Child animations don't work in React 19 StrictMode Source: https://github.com/formkit/auto-animate/issues/232 Why It Happens: StrictMode calls useEffect twice, triggering autoAnimate initialization twice Prevention: Use ref to track initialization

// ❌ Wrong - breaks in StrictMode
const [parent] = useAutoAnimate();

// ✅ Correct - prevents double initialization
const [parent] = useAutoAnimate();
const initialized = useRef(false);

useEffect(() => {
  if (initialized.current) return;
  initialized.current = true;
}, []);

Note: React 19 enables StrictMode by default in development. This affects all React 19+ projects.

Issue #12: Broken Animation Outside Viewport

Error: Animations broken when list is outside viewport Source: https://github.com/formkit/auto-animate/issues/222 Why It Happens: Chrome may not run Animation API for off-screen elements Prevention: Ensure parent is visible before applying autoAnimate

const isInViewport = (element) => {
  const rect = element.getBoundingClientRect();
  return rect.top >= 0 && rect.bottom <= window.innerHeight;
};

useEffect(() => {
  if (parent.current && isInViewport(parent.current)) {
    autoAnimate(parent.current);
  }
}, [parent]);

Issue #13: Deleted Elements Overlay Existing Content

Error: Removed items overlay other items during fade out Source: https://github.com/formkit/auto-animate/issues/231 Why It Happens: Exit animation maintains z-index, covering active content Prevention: Add explicit z-index handling

// CSS workaround
<style>{`
  [data-auto-animate-target] {
    z-index: -1 !important;
  }
`}</style>

Issue #14: Cannot Disable During Drag & Drop

Error: Calling enable(false) doesn't prevent animations during drag Source: https://github.com/formkit/auto-animate/issues/215 Why It Happens: Disable doesn't work reliably mid-drag Prevention: Conditionally remove ref during drag

const [isDragging, setIsDragging] = useState(false);
const [parent] = useAutoAnimate();

return (
  <ul ref={isDragging ? null : parent}>
    {/* items */}
  </ul>
);

Issue #15: CSS Transform Parent Position Bug

Error: Items animate from wrong position after parent transform Source: https://github.com/formkit/auto-animate/issues/227 Why It Happens: Items remember original position before transform Prevention: Delay autoAnimate until transform completes

useEffect(() => {
  if (showList && parent.current) {
    setTimeout(() => {
      autoAnimate(parent.current);
    }, 300); // Match CSS transition duration
  }
}, [showList]);

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Critical Rules (Error Prevention)

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 breaks accessibility ❌ Animate tables directly - Use tbody or div-based layout ❌ Skip unique keys - Required for proper animation ❌ Complex animations - Use Motion instead

Note: AutoAnimate respects prefers-reduced-motion automatically (never disable this).

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Community Tips (Community-Sourced)

Note: These tips come from community discussions. Verify against your version.

Tip: Prevent Test Freezing with Mocked Package

Source: Issue #230 | Confidence: MEDIUM Applies to: v0.8.2+

Tests may freeze for ~10 seconds when package is mocked. Add ResizeObserver mock:

// jest.setup.js
global.ResizeObserver = jest.fn().mockImplementation(() => ({
  observe: jest.fn(),
  unobserve: jest.fn(),
  disconnect: jest.fn(),
}));

// __mocks__/@formkit/auto-animate.js
const autoAnimate = jest.fn(() => () => {});
const useAutoAnimate = jest.fn(() => [null, jest.fn(), jest.fn()]);
module.exports = { default: autoAnimate, useAutoAnimate };

Tip: Memory Leak Prevention

Source: Issue #180 | Confidence: LOW Applies to: All versions

For long-lived SPAs, ensure proper cleanup:

useEffect(() => {
  const cleanup = autoAnimate(parent.current);
  return () => cleanup && cleanup();
}, []);

// useAutoAnimate hook 

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