fix(docs-infra): do not break when cookies are disabled in the browser (#33829)

Whenever cookies are disabled in the browser, `window.sessionStorage` is not avaialable to the app (i.e. even trying to access `window.sessionStorage` throws an error).

To avoid breaking the app, we use a no-op `Storage` implementation if `window.sessionStorage` is not available.

Fixes #33795

PR Close #33829

aio/src/app/shared/scroll.service.spec.ts

@@ -94,6 +94,22 @@ describe('ScrollService', () => {
     }
   });
 
+  it('should not break when cookies are disabled in the browser', () => {
+    // Simulate `window.sessionStorage` being inaccessible, when cookies are disabled.
+    spyOnProperty(window, 'sessionStorage', 'get').and.throwError('The operation is insecure');
+
+    expect(() => {
+      const platformLoc = platformLocation as PlatformLocation;
+      const service = new ScrollService(document, platformLoc, viewportScrollerStub, location);
+
+      service.updateScrollLocationHref();
+      expect(service.getStoredScrollLocationHref()).toBeNull();
+
+      service.removeStoredScrollInfo();
+      expect(service.getStoredScrollPosition()).toBeNull();
+    }).not.toThrow();
+  });
+
   describe('#topOffset', () => {
     it('should query for the top-bar by CSS selector', () => {
       expect(document.querySelector).not.toHaveBeenCalled();

aio/src/app/shared/scroll.service.ts

@@ -19,6 +19,7 @@ export class ScrollService implements OnDestroy {
   private _topOffset: number | null;
   private _topOfPageElement: Element;
   private onDestroy = new Subject<void>();
+  private storage: Storage;
 
   // The scroll position which has to be restored, after a `popstate` event.
   poppedStateScrollPosition: ScrollPosition | null = null;
@@ -49,6 +50,21 @@ export class ScrollService implements OnDestroy {
       private platformLocation: PlatformLocation,
       private viewportScroller: ViewportScroller,
       private location: Location) {
+    try {
+      this.storage = window.sessionStorage;
+    } catch {
+      // When cookies are disabled in the browser, even trying to access
+      // `window.sessionStorage` throws an error. Use a no-op storage.
+      this.storage = {
+        length: 0,
+        clear: () => undefined,
+        getItem: () => null,
+        key: () => null,
+        removeItem: () => undefined,
+        setItem: () => undefined
+      };
+    }
+
     // On resize, the toolbar might change height, so "invalidate" the top offset.
     fromEvent(window, 'resize')
         .pipe(takeUntil(this.onDestroy))
@@ -180,7 +196,7 @@ export class ScrollService implements OnDestroy {
   }
 
   updateScrollLocationHref(): void {
-    window.sessionStorage.setItem('scrollLocationHref', window.location.href);
+    this.storage.setItem('scrollLocationHref', window.location.href);
   }
 
   /**
@@ -190,17 +206,17 @@ export class ScrollService implements OnDestroy {
     if (this.supportManualScrollRestoration) {
       const currentScrollPosition = this.viewportScroller.getScrollPosition();
       this.location.replaceState(this.location.path(true), undefined, {scrollPosition: currentScrollPosition});
-      window.sessionStorage.setItem('scrollPosition', currentScrollPosition.join(','));
+      this.storage.setItem('scrollPosition', currentScrollPosition.join(','));
     }
   }
 
   getStoredScrollLocationHref(): string | null {
-    const href = window.sessionStorage.getItem('scrollLocationHref');
+    const href = this.storage.getItem('scrollLocationHref');
     return href || null;
   }
 
   getStoredScrollPosition(): ScrollPosition | null {
-    const position = window.sessionStorage.getItem('scrollPosition');
+    const position = this.storage.getItem('scrollPosition');
     if (!position) { return null; }
 
     const [x, y] = position.split(',');
@@ -208,8 +224,8 @@ export class ScrollService implements OnDestroy {
   }
 
   removeStoredScrollInfo() {
-    window.sessionStorage.removeItem('scrollLocationHref');
-    window.sessionStorage.removeItem('scrollPosition');
+    this.storage.removeItem('scrollLocationHref');
+    this.storage.removeItem('scrollPosition');
   }
 
   /**