demo · v142

Active VT

Trigger a real view transition and watch document.activeViewTransition flip from null to a live ViewTransition object and back. Double-click "swap fast" — the guard skips the second one.

document.activeViewTransition
null
phase
idle
A

relevant API

function safeStart(updateDOM) {
  if (document.activeViewTransition) return; // a transition is in flight
  if (!document.startViewTransition) { updateDOM(); return; }
  document.startViewTransition(updateDOM);
}

see also