The ViewTransition interface of the View Transition API represents an active view transition, and provides functionality to react to the transition reaching different states (e.g., ready to run the animation, or animation finished) or skip the transition altogether.
This object type is made available in the following ways:
Document.activeViewTransition property. This provides a consistent way to access the active view transition in any context, without having to worry about saving it for easy access later on.document.startViewTransition() method.pageswap event object's PageSwapEvent.viewTransition property.pagereveal event object's PageRevealEvent.viewTransition property.When a view transition is triggered by a startViewTransition() call (or a page navigation in the case of MPA transitions), a sequence of steps is followed as explained in The view transition process. This also explains when the different promises fulfill.
ViewTransition.finished Read onlyA Promise that fulfills once the transition animation is finished, and the new page view is visible and interactive to the user.
ViewTransition.ready Read onlyA Promise that fulfills once the pseudo-element tree is created and the transition animation is about to start.
ViewTransition.transitionRoot Read only A reference to the root Element of the view transition scope.
ViewTransition.types Read onlyA ViewTransitionTypeSet that allows the types set on the view transition to be accessed and modified.
ViewTransition.updateCallbackDone Read onlyA Promise that fulfills when the promise returned by the document.startViewTransition() method's callback fulfills.
skipTransition()Skips the animation part of the view transition, but doesn't skip running the document.startViewTransition() callback that updates the DOM.
waitUntil() Delays finishing the view transition and the destruction of the associated pseudo-element tree until a Promise passed into the method has resolved.
In the following SPA example, the ViewTransition.ready promise is used to trigger a custom circular reveal view transition emanating from the position of the user's cursor on click, with animation provided by the Web Animations API.
// Store the last click event
let lastClick;
addEventListener("click", (event) => (lastClick = event));
function spaNavigate(data) {
// Fallback for browsers that don't support this API:
if (!document.startViewTransition) {
updateTheDOMSomehow(data);
return;
}
// Get the click position, or fallback to the middle of the screen
const x = lastClick?.clientX ?? innerWidth / 2;
const y = lastClick?.clientY ?? innerHeight / 2;
// Get the distance to the furthest corner
const endRadius = Math.hypot(
Math.max(x, innerWidth - x),
Math.max(y, innerHeight - y),
);
// Create a transition:
const transition = document.startViewTransition(() => {
updateTheDOMSomehow(data);
});
// Wait for the pseudo-elements to be created:
transition.ready.then(() => {
// Animate the root's new view
document.documentElement.animate(
{
clipPath: [
`circle(0 at ${x}px ${y}px)`,
`circle(${endRadius}px at ${x}px ${y}px)`,
],
},
{
duration: 500,
easing: "ease-in",
// Specify which pseudo-element to animate
pseudoElement: "::view-transition-new(root)",
},
);
});
}This animation also requires the following CSS, to turn off the default CSS animation and stop the old and new view states from blending in any way (the new state "wipes" right over the top of the old state, rather than transitioning in):
::view-transition-image-pair(root) {
isolation: auto;
}
::view-transition-old(root),
::view-transition-new(root) {
animation: none;
mix-blend-mode: normal;
display: block;
}