Gsap React

When @gsap/react is available, use the useGSAP() hook instead of useEffect() for GSAP setup. It handles cleanup automatically and provides a scope and contextSafe for callbacks.

import { useGSAP } from '@gsap/react'

gsap.registerPlugin(useGSAP) // register before running useGSAP or any GSAP code

const containerRef = useRef(null)

useGSAP(
  () => {
    gsap.to('.box', { x: 100 })
    gsap.from('.item', { opacity: 0, stagger: 0.1 })
  },
  { scope: containerRef }
)

• ✅ Pass a scope (ref or element) so selectors like .box are scoped to that root.
• ✅ Cleanup (reverting animations and ScrollTriggers) runs automatically on unmount.
• ✅ Use contextSafe from the hook's return value to wrap callbacks (e.g. onComplete) so they no-op after unmount and avoid React warnings.

Refs for Targets

Use refs so GSAP targets the actual DOM nodes after render. Do not rely on selector strings that might match multiple or wrong elements across re-renders unless a scope is defined. With useGSAP, pass the ref as scope; with useEffect, pass it as the second argument to gsap.context(). For multiple elements, use a ref to the container and query children, or use an array of refs.

Dependency array, scope, and revertOnUpdate

By default, useGSAP() passes an empty dependency array to the internal useEffect()/useLayoutEffect() so that it doesn't get called on every render. The 2nd argument is optional; it can pass either a dependency array (like useEffect()) or a config object for more flexibility:

useGSAP(
  () => {
    // gsap code here, just like in a useEffect()
  },
  {
    dependencies: [endX], // dependency array (optional)
    scope: container, // scope selector text (optional, recommended)
    revertOnUpdate: true, // causes the context to be reverted and the cleanup function to run every time the hook re-synchronizes (when any dependency changes)
  }
)

gsap.context() in useEffect (when useGSAP isn't used)

It's okay to use gsap.context() inside a regular useEffect() when @gsap/react is not used or when the effect's dependency/trigger behavior is needed. When doing so, always call ctx.revert() in the effect's cleanup function so animations and ScrollTriggers are killed and inline styles are reverted. Otherwise this causes leaks and updates on detached nodes.

useEffect(() => {
  const ctx = gsap.context(() => {
    gsap.to('.box', { x: 100 })
    gsap.from('.item', { opacity: 0, stagger: 0.1 })
  }, containerRef)
  return () => ctx.revert()
}, [])

• ✅ Pass a scope (ref or element) as the second argument so selectors are scoped to that node.
• ✅ Always return a cleanup that calls ctx.revert().

Context-Safe Callbacks

If GSAP-related objects get created inside functions that run AFTER the useGSAP executes (like pointer event handlers) they won't get reverted on unmount/re-render because they're not in the context. Use contextSafe (from useGSAP) for those functions:

const container = useRef()
const badRef = useRef()
const goodRef = useRef()

useGSAP(
  (context, contextSafe) => {
    // ✅ safe, created during execution
    gsap.to(goodRef.current, { x: 100 })

    // ❌ DANGER! This animation is created in an event handler that executes AFTER useGSAP() executes. It's not added to the context so it won't get cleaned up (reverted). The event listener isn't removed in cleanup function below either, so it persists between component renders (bad).
    badRef.current.addEventListener('click', () => {
      gsap.to(badRef.current, { y: 100 })
    })

    // ✅ safe, wrapped in contextSafe() function
    const onClickGood = contextSafe(() => {
      gsap.to(goodRef.current, { rotation: 180 })
    })

    goodRef.current.addEventListener('click', onClickGood)

    // 👍 we remove the event listener in the cleanup function below.
    return () => {
      // <-- cleanup
      goodRef.current.removeEventListener('click', onClickGood)
    }
  },
  { scope: container }
)

Server-Side Rendering (Next.js, etc.)

GSAP runs in the browser. Do not call gsap or ScrollTrigger during SSR.

• Use useGSAP (or useEffect) so all GSAP code runs only on the client.
• If GSAP is imported at top level, ensure the app does not execute gsap._ or ScrollTrigger._ during server render. Dynamic import inside useEffect is an option if tree-shaking or bundle size is a concern.

Best practices

• ✅ Prefer useGSAP() from @gsap/react rather than useEffect()/useLayoutEffect(); use gsap.context() + ctx.revert() in useEffect when useGSAP is not an option.
• ✅ Use refs for targets and pass a scope so selectors are limited to the component.
• ✅ Run GSAP only on the client (useGSAP or useEffect); do not call gsap or ScrollTrigger during SSR.

Do Not

• ❌ Target by selector without a scope; always pass scope (ref or element) in useGSAP or gsap.context() so selectors like .box are limited to that root and do not match elements outside the component.
• ❌ Animate using selector strings that can match elements outside the current component unless a scope is defined in useGSAP or gsap.context() so only elements inside the component are affected.
• ❌ Skip cleanup; always revert context or kill tweens/ScrollTriggers in the effect return to avoid leaks and updates on unmounted nodes.
• ❌ Run GSAP or ScrollTrigger during SSR; keep all usage inside client-only lifecycle (e.g. useGSAP).

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