Function startViewTransition

packages/@react-spectrum/s2/src/Toast.tsx:84–101

(fn: () => void, type: string)

let globalReduceMotion = false;
function startViewTransition(fn: () => void, type: string) {
  if ('startViewTransition' in document) {
    // Safari doesn't support :active-view-transition-type() yet, so we fall back to a class on the html element.
    document.documentElement.classList.add(toastCss[type]);
    if (globalReduceMotion) {
      document.documentElement.classList.add(toastCss.reduceMotion);
    }

    let viewTransition = document.startViewTransition(() => flushSync(fn));

    viewTransition.ready.catch(() => {});
    viewTransition.finished.then(() => {
      document.documentElement.classList.remove(toastCss[type], toastCss.reduceMotion);
    });
  } else {
    fn();
  }
}

// There is a single global toast queue instance for the whole app, initialized lazily.
let globalToastQueue: ToastQueue<SpectrumToastValue> | null = null;