Function handler

fixtures/view-transition/src/components/App.js:43–64

()

        const newURL = new URL(event.destination.url);
        event.intercept({
          handler() {
            let promise;
            startTransition(() => {
              addTransitionType('navigation-' + navigationType);
              if (navigationType === 'traverse') {
                // For traverse types it's useful to distinguish going back or forward.
                const nextIndex = event.destination.index;
                if (nextIndex > previousIndex) {
                  addTransitionType('navigation-forward');
                } else if (nextIndex < previousIndex) {
                  addTransitionType('navigation-back');
                }
              }
              promise = new Promise(resolve => {
                setRouterState({
                  url: newURL.pathname + newURL.search,
                  pendingNav: resolve,
                });
              });
            });
            return promise;
          },
          commit: 'after-transition', // plz ship this, browsers
        });
      });