vercel-react-view-transitions Checked

• **Next.js:** Do **not** install react@canary — the App Router already bundles React canary internally. ViewTransition works out of the box. npm ls react may show a stable-looking version; this is expected.
• **Without Next.js:** Install react@canary react-dom@canary (ViewTransition is not in stable React).
• Browser support: Chromium 125+ (React needs the v2 object form of startViewTransition), Firefox 144+, Safari 18.2+. Graceful degradation on unsupported browsers.

---

Implementation Workflow

When adding view transitions to an existing app, **follow references/implementation.md (references/implementation.md) step by step.** Start with the audit — do not skip it. Use references/css-recipes.md (references/css-recipes.md) for the applicable CSS and adapt it to the app.

---

Core Concepts

### The <ViewTransition> Component

import { ViewTransition } from 'react';

<ViewTransition>
  <Component />
</ViewTransition>

React auto-assigns a unique view-transition-name and calls document.startViewTransition behind the scenes. Never call startViewTransition yourself.

### Animation Triggers

| Trigger | When it fires |

|---------|--------------|

| **enter** | <ViewTransition> first inserted during a Transition |

| **exit** | <ViewTransition> first removed during a Transition |

| **update** | DOM mutations inside a <ViewTransition>, or the boundary itself changing size/position due to an immediate sibling. With nested VTs, mutation applies to the innermost one |

| **share** | Named VT unmounts and another with same name mounts in the same Transition |

Only startTransition, useDeferredValue, or Suspense activate VTs. Regular setState does not animate.

### Critical Placement Rule

<ViewTransition> only activates enter/exit if it appears **before any DOM nodes**:

// Works
<ViewTransition enter="auto" exit="auto">
  <div>Content</div>
</ViewTransition>

// Broken — div wraps the VT, suppressing enter/exit
<div>
  <ViewTransition enter="auto" exit="auto">
    <div>Content</div>
  </ViewTransition>
</div>

---

Styling with View Transition Classes

### Props

Values: "auto" (browser cross-fade), "none" (disabled), "class-name" (custom CSS), or { [type]: value } for type-specific animations.

<ViewTransition default="none" enter="slide-in" exit="slide-out" share="morph" />

If default is "none", all triggers are off unless explicitly listed.

### CSS Pseudo-Elements

• ::view-transition-old(.class) — outgoing snapshot
• ::view-transition-new(.class) — incoming snapshot
• ::view-transition-group(.class) — container
• ::view-transition-image-pair(.class) — old + new pair

See references/css-recipes.md (references/css-recipes.md) for ready-to-use animation recipes.

---

Transition Types

Tag transitions with addTransitionType so VTs can pick different animations based on context. Call it multiple times to stack types — different VTs in the tree react to different types:

startTransition(() => {
  addTransitionType('nav-forward');
  addTransitionType('select-item');
  router.push('/detail/1');
});

Pass an object to map types to CSS classes. Works on enter, exit, **and** share:

<ViewTransition
  enter={{ 'nav-forward': 'slide-from-right', 'nav-back': 'slide-from-left', default: 'none' }}
  exit={{ 'nav-forward': 'slide-to-left', 'nav-back': 'slide-to-right', default: 'none' }}
  share={{ 'nav-forward': 'morph-forward', 'nav-back': 'morph-back', default: 'morph' }}
  default="none"
>
  <Page />
</ViewTransition>

enter and exit don't have to be symmetric. For example, fade in but slide out directionally:

<ViewTransition
  enter={{ 'nav-forward': 'fade-in', 'nav-back': 'fade-in', default: 'none' }}
  exit={{ 'nav-forward': 'nav-forward', 'nav-back': 'nav-back', default: 'none' }}
  default="none"
>

**TypeScript:** ViewTransitionClassPerType requires a default key in the object.

For apps with multiple pages, extract the type-keyed VT into a reusable wrapper:

export function DirectionalTransition({ children }: { children: React.ReactNode }) {
  return (
    <ViewTransition
      enter={{ 'nav-forward': 'nav-forward', 'nav-back': 'nav-back', default: 'none' }}
      exit={{ 'nav-forward': 'nav-forward', 'nav-back': 'nav-back', default: 'none' }}
      default="none"
    >
      {children}
    </ViewTransition>
  );
}

### router.back() and Browser Back Button

router.back() and the browser's back/forward buttons carry **no transition types**, so type-keyed animations (directional slides) resolve to their default and don't play — untyped shared-element morphs still apply. For typed animations, use router.push() with an explicit URL.

### Types and Suspense

Types are available during navigation but **not** during subsequent Suspense reveals (separate transitions, no type). Use type maps for page-level enter/exit; use simple string props for Suspense reveals.

### Shared Element Readiness

A shared element transition can pair elements only when both the old and new views are rendered in the same Transition. If incoming content suspends, only its fallback exists for that update; the resolved content appears in a later Suspense transition and can be animated separately.

---

Shared Element Transitions

Same name on two VTs — one unmounting, one mounting — creates a shared element morph:

<ViewTransition name="hero-image">
  <img src="/thumb.jpg" onClick={() => startTransition(() => onSelect())} />
</ViewTransition>

// On the other view — same name
<ViewTransition name="hero-image">
  <img src="/full.jpg" />
</ViewTransition>

• Only one VT with a given name can be mounted at a time — use unique names (photo-${id}). Watch for reusable components: if a component with a named VT is rendered in both a modal/popover *and* a page, both mount simultaneously and break the morph. Either make the name conditional (via a prop) or move the named VT