"Close requests" are a new concept that encompasses user requests to close something currently open, using the Esc key on desktop or the back gesture/button on Android.
const watcher = new CloseWatcher();
// This fires when the user sends a close request, e.g. by pressing Esc on
// desktop or by pressing Android's back button.
watcher.onclose = () => {
myModal.close();
};
// You should destroy watchers which are no longer needed, e.g. if the
// modal closes normally. This will prevent future events on this watcher.
myModalCloseButton.onclick = () => {
watcher.destroy();
myModal.close();
};