fix(aio): show embedded ToC (#23944)

On narrow screens (where there is not enough room on the right to show
the floating ToC), an embedded ToC is shown (via an `<aio-toc embedded>`
element in the document). Since ToC was not a custom element, the
component was not instantiated for the embedded element.

This commit fixes it by making `aio-toc` a custom element and loading it
manually for the floating ToC (if necessary).

PR Close #23944

aio/scripts/_payload-limits.json

@@ -2,8 +2,8 @@
   "aio": {
     "master": {
       "uncompressed": {
-        "runtime": 2712,
+        "runtime": 2768,
-        "main": 479729,
+        "main": 475857,
         "polyfills": 38453,
         "prettify": 14913
       }

aio/src/app/app.component.html

@@ -58,7 +58,7 @@
 </mat-sidenav-container>
 
 <div *ngIf="hasFloatingToc" class="toc-container no-print" [style.max-height.px]="tocMaxHeight" (mousewheel)="restrainScrolling($event)">
-  <aio-toc></aio-toc>
+  <aio-lazy-ce selector="aio-toc"></aio-lazy-ce>
 </div>
 
 <footer class="no-print">

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

@@ -6,7 +6,7 @@ import { HttpClient } from '@angular/common/http';
 import { MatProgressBar, MatSidenav } from '@angular/material';
 import { By } from '@angular/platform-browser';
 
-import { timer } from 'rxjs';
+import { of, timer } from 'rxjs';
 import { first, mapTo } from 'rxjs/operators';
 
 import { AppComponent } from './app.component';
@@ -14,6 +14,7 @@ import { AppModule } from './app.module';
 import { DocumentService } from 'app/documents/document.service';
 import { DocViewerComponent } from 'app/layout/doc-viewer/doc-viewer.component';
 import { Deployment } from 'app/shared/deployment.service';
+import { ElementsLoader } from 'app/custom-elements/elements-loader';
 import { GaService } from 'app/shared/ga.service';
 import { LocationService } from 'app/shared/location.service';
 import { Logger } from 'app/shared/logger.service';
@@ -26,7 +27,6 @@ import { SearchBoxComponent } from 'app/search/search-box/search-box.component';
 import { SearchResultsComponent } from 'app/shared/search-results/search-results.component';
 import { SearchService } from 'app/search/search.service';
 import { SelectComponent } from 'app/shared/select/select.component';
-import { TocComponent } from 'app/layout/toc/toc.component';
 import { TocItem, TocService } from 'app/shared/toc.service';
 
 const sideBySideBreakPoint = 992;
@@ -621,53 +621,53 @@ describe('AppComponent', () => {
     });
 
     describe('aio-toc', () => {
-      let tocDebugElement: DebugElement;
+      let tocContainer: HTMLElement|null;
-      let tocContainer: DebugElement|null;
+      let toc: HTMLElement|null;
 
       const setHasFloatingToc = (hasFloatingToc: boolean) => {
         component.hasFloatingToc = hasFloatingToc;
         fixture.detectChanges();
 
-        tocDebugElement = fixture.debugElement.query(By.directive(TocComponent));
+        tocContainer = fixture.debugElement.nativeElement.querySelector('.toc-container');
-        tocContainer = tocDebugElement && tocDebugElement.parent;
+        toc = tocContainer && tocContainer.querySelector('aio-toc');
       };
 
       beforeEach(() => setHasFloatingToc(true));
 
 
       it('should show/hide `<aio-toc>` based on `hasFloatingToc`', () => {
-        expect(tocDebugElement).toBeTruthy();
         expect(tocContainer).toBeTruthy();
+        expect(toc).toBeTruthy();
 
         setHasFloatingToc(false);
-        expect(tocDebugElement).toBeFalsy();
         expect(tocContainer).toBeFalsy();
+        expect(toc).toBeFalsy();
 
         setHasFloatingToc(true);
-        expect(tocDebugElement).toBeTruthy();
         expect(tocContainer).toBeTruthy();
+        expect(toc).toBeTruthy();
       });
 
       it('should have a non-embedded `<aio-toc>` element', () => {
-        expect(tocDebugElement.classes['embedded']).toBeFalsy();
+        expect(toc!.classList.contains('embedded')).toBe(false);
       });
 
       it('should update the TOC container\'s `maxHeight` based on `tocMaxHeight`', () => {
-        expect(tocContainer!.styles['max-height']).toBeNull();
+        expect(tocContainer!.style['max-height']).toBe('');
 
         component.tocMaxHeight = '100';
         fixture.detectChanges();
 
-        expect(tocContainer!.styles['max-height']).toBe('100px');
+        expect(tocContainer!.style['max-height']).toBe('100px');
       });
 
       it('should restrain scrolling inside the ToC container', () => {
         const restrainScrolling = spyOn(component, 'restrainScrolling');
-        const evt = {};
+        const evt = new MouseEvent('mousewheel');
 
         expect(restrainScrolling).not.toHaveBeenCalled();
 
-        tocContainer!.triggerEventHandler('mousewheel', evt);
+        tocContainer!.dispatchEvent(evt);
         expect(restrainScrolling).toHaveBeenCalledWith(evt);
       });
     });
@@ -1280,6 +1280,7 @@ function createTestingModule(initialUrl: string, mode: string = 'stable') {
     imports: [ AppModule ],
     providers: [
       { provide: APP_BASE_HREF, useValue: '/' },
+      { provide: ElementsLoader, useClass: TestElementsLoader },
       { provide: GaService, useClass: TestGaService },
       { provide: HttpClient, useClass: TestHttpClient },
       { provide: LocationService, useFactory: () => mockLocationService },
@@ -1294,6 +1295,14 @@ function createTestingModule(initialUrl: string, mode: string = 'stable') {
   });
 }
 
+class TestElementsLoader {
+  loadContainingCustomElements = jasmine.createSpy('loadContainingCustomElements')
+      .and.returnValue(of(undefined));
+
+  loadCustomElement = jasmine.createSpy('loadCustomElement')
+      .and.returnValue(Promise.resolve());
+}
+
 class TestGaService {
   locationChanged = jasmine.createSpy('locationChanged');
 }

aio/src/app/app.module.ts

@@ -32,7 +32,6 @@ import { ScrollService } from 'app/shared/scroll.service';
 import { ScrollSpyService } from 'app/shared/scroll-spy.service';
 import { SearchBoxComponent } from 'app/search/search-box/search-box.component';
 import { NotificationComponent } from 'app/layout/notification/notification.component';
-import { TocComponent } from 'app/layout/toc/toc.component';
 import { TocService } from 'app/shared/toc.service';
 import { CurrentDateToken, currentDateProvider } from 'app/shared/current-date';
 import { WindowToken, windowProvider } from 'app/shared/window';
@@ -111,7 +110,6 @@ export const svgIconProviders = [
     NavItemComponent,
     SearchBoxComponent,
     NotificationComponent,
-    TocComponent,
     TopMenuComponent,
   ],
   providers: [
@@ -133,7 +131,6 @@ export const svgIconProviders = [
     { provide: CurrentDateToken, useFactory: currentDateProvider },
     { provide: WindowToken, useFactory: windowProvider },
   ],
-  entryComponents: [ TocComponent ],
   bootstrap: [ AppComponent ]
 })
 export class AppModule { }

aio/src/app/custom-elements/element-registry.ts

@@ -24,6 +24,10 @@ export const ELEMENT_MODULE_PATHS_AS_ROUTES = [
     selector: 'aio-resource-list',
     loadChildren: './resource/resource-list.module#ResourceListModule'
   },
+  {
+    selector: 'aio-toc',
+    loadChildren: './toc/toc.module#TocModule'
+  },
   {
     selector: 'code-example',
     loadChildren: './code/code-example.module#CodeExampleModule'

aio/src/app/custom-elements/toc/toc.component.spec.ts

@@ -4,8 +4,8 @@ import { By } from '@angular/platform-browser';
 import { asapScheduler as asap, BehaviorSubject } from 'rxjs';
 
 import { ScrollService } from 'app/shared/scroll.service';
-import { TocComponent } from './toc.component';
 import { TocItem, TocService } from 'app/shared/toc.service';
+import { TocComponent } from './toc.component';
 
 describe('TocComponent', () => {
   let tocComponentDe: DebugElement;

aio/src/app/custom-elements/toc/toc.module.ts

@@ -0,0 +1,14 @@
+import { NgModule, Type } from '@angular/core';
+import { CommonModule } from '@angular/common';
+import { MatIconModule } from '@angular/material/icon';
+import { WithCustomElementComponent } from '../element-registry';
+import { TocComponent } from './toc.component';
+
+@NgModule({
+  imports: [ CommonModule, MatIconModule ],
+  declarations: [ TocComponent ],
+  entryComponents: [ TocComponent ],
+})
+export class TocModule implements WithCustomElementComponent {
+  customElementComponent: Type<any> = TocComponent;
+}