The transition read-only property of the Navigation interface returns a NavigationTransition object representing the status of an in-progress navigation, which can be used to track it.
Navigation.transition is only populated while the intercept() handler is unresolved (i.e., during a navigation interception), and is otherwise null.
A NavigationTransition object, or null if no navigation is currently in progress.
async function handleTransition() {
if (navigation.transition) {
showLoadingSpinner();
await navigation.transition.finished;
hideLoadingSpinner();
}
}