fix(aio): correctly handle re-navigation to the empty path (#16997)

aio/src/app/app.component.spec.ts

@@ -401,6 +401,22 @@ describe('AppComponent', () => {
         expect(scrollSpy.calls.count()).toBe(2);
       });
 
+      it('should scroll when nav to the same path', () => {
+        locationService.go('guide/pipes');
+        scrollSpy.calls.reset();
+
+        locationService.go('guide/pipes');
+        expect(scrollSpy).toHaveBeenCalledTimes(1);
+      });
+
+      it('should scroll when e-nav to the empty path', () => {
+        locationService.go('');
+        scrollSpy.calls.reset();
+
+        locationService.go('');
+        expect(scrollSpy).toHaveBeenCalledTimes(1);
+      });
+
       it('should scroll after a delay when call onDocRendered directly', fakeAsync(() => {
         component.onDocRendered();
         expect(scrollSpy).not.toHaveBeenCalled();
@@ -650,6 +666,20 @@ describe('AppComponent', () => {
         expect(getProgressBar()).toBeFalsy();
       }));
 
+      it('should not be shown when re-navigating to the empty path', fakeAsync(() => {
+        initializeAndCompleteNavigation();
+        locationService.urlSubject.next('');
+        triggerDocRendered();
+
+        locationService.urlSubject.next('');
+
+        tick(SHOW_DELAY);
+        fixture.detectChanges();
+        expect(getProgressBar()).toBeFalsy();
+
+        tick(HIDE_DELAY);   // Fire the remaining timer or `fakeAsync()` complains.
+      }));
+
       it('should not be shown if the doc is rendered quickly', fakeAsync(() => {
         initializeAndCompleteNavigation();
         locationService.urlSubject.next('c/d');

aio/src/app/app.component.ts

@@ -123,7 +123,7 @@ export class AppComponent implements OnInit {
     });
 
     this.locationService.currentPath.subscribe(path => {
-      if (this.currentPath && path === this.currentPath) {
+      if (path === this.currentPath) {
         // scroll only if on same page (most likely a change to the hash)
         this.autoScroll();
       } else {