if ('serviceWorker' in navigator) {
  window.addEventListener('load', function () {
    navigator.serviceWorker.register('/serviceWorker.js').then(function (registration) {
      console.log('ServiceWorker registration successful with scope: ', registration.scope);
      registration.update().then(res => {
        console.log('ServiceWorker registration update: ', res);
      });
    }, function (err) {
      console.error('ServiceWorker registration failed: ', err);
    });
    navigator.serviceWorker.addEventListener('controllerchange', function() {
      console.log('ServiceWorker controllerchange ');
      window.location.reload(true);
    });
  });
}