Function subscribe

packages/dev/s2-docs/src/Router.tsx:19–24

(callback: () => void)

};

export function subscribe(callback: () => void) {
  listeners.add(callback);
  return () => {
    listeners.delete(callback);
  };
}

export function getSnapshot() {
  if (cachedSnapshot.promise !== navigationPromise || cachedSnapshot.pathname !== targetPathname) {