feat(core): add DoBootstrap interface. (#24558)

Closes #24557.

PR Close #24558

packages/core/src/metadata.ts

@@ -13,11 +13,11 @@
 
 import {Attribute, ContentChild, ContentChildren, Query, ViewChild, ViewChildren} from './metadata/di';
 import {Component, Directive, HostBinding, HostListener, Input, Output, Pipe} from './metadata/directives';
-import {ModuleWithProviders, NgModule, SchemaMetadata} from './metadata/ng_module';
+import {DoBootstrap, ModuleWithProviders, NgModule, SchemaMetadata} from './metadata/ng_module';
 import {ViewEncapsulation} from './metadata/view';
 
 export {ANALYZE_FOR_ENTRY_COMPONENTS, Attribute, ContentChild, ContentChildDecorator, ContentChildren, ContentChildrenDecorator, Query, ViewChild, ViewChildDecorator, ViewChildren, ViewChildrenDecorator} from './metadata/di';
 export {Component, ComponentDecorator, Directive, DirectiveDecorator, HostBinding, HostListener, Input, Output, Pipe} from './metadata/directives';
 export {AfterContentChecked, AfterContentInit, AfterViewChecked, AfterViewInit, DoCheck, OnChanges, OnDestroy, OnInit} from './metadata/lifecycle_hooks';
-export {CUSTOM_ELEMENTS_SCHEMA, ModuleWithProviders, NO_ERRORS_SCHEMA, NgModule, SchemaMetadata} from './metadata/ng_module';
+export {CUSTOM_ELEMENTS_SCHEMA, DoBootstrap, ModuleWithProviders, NO_ERRORS_SCHEMA, NgModule, SchemaMetadata} from './metadata/ng_module';
 export {ViewEncapsulation} from './metadata/view';

packages/core/src/metadata/ng_module.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {ApplicationRef} from '../application_ref';
 import {InjectorDef, InjectorType, defineInjector} from '../di/defs';
 import {convertInjectableProviderToFactory} from '../di/injectable';
 import {Provider} from '../di/provider';
@@ -352,3 +353,24 @@ export const NgModule: NgModuleDecorator = makeDecorator(
      * this module's members available to others.
      */
     (type: Type<any>, meta: NgModule) => (R3_COMPILE_NGMODULE || preR3NgModuleCompile)(type, meta));
+
+/**
+ * @description
+ * Hook for manual bootstrapping of the application instead of using bootstrap array in @NgModule
+ * annotation.
+ *
+ * Reference to the current application is provided as a parameter.
+ *
+ * See ["Bootstrapping"](guide/bootstrapping) and ["Entry components"](guide/entry-components).
+ *
+ * @usageNotes
+ * ```typescript
+ * class AppModule implements DoBootstrap {
+ *   ngDoBootstrap(appRef: ApplicationRef) {
+ *     appRef.bootstrap(AppComponent); // Or some other component
+ *   }
+ * }
+ * ```
+ *
+ */
+export interface DoBootstrap { ngDoBootstrap(appRef: ApplicationRef): void; }

packages/elements/test/create-custom-element_spec.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Component, EventEmitter, Injector, Input, NgModule, Output, destroyPlatform} from '@angular/core';
+import {Component, DoBootstrap, EventEmitter, Injector, Input, NgModule, Output, destroyPlatform} from '@angular/core';
 import {BrowserModule} from '@angular/platform-browser';
 import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
 import {Subject} from 'rxjs';
@@ -109,13 +109,12 @@ class TestComponent {
   @Output() bazBaz = new EventEmitter<boolean>();
   @Output('quxqux') quxQux = new EventEmitter<Object>();
 }
-
 @NgModule({
   imports: [BrowserModule],
   declarations: [TestComponent],
   entryComponents: [TestComponent],
 })
-class TestModule {
+class TestModule implements DoBootstrap {
   ngDoBootstrap() {}
 }
 

tools/public_api_guard/core/core.d.ts

@@ -267,6 +267,10 @@ export interface DirectiveDecorator {
     new (obj: Directive): Directive;
 }
 
+export interface DoBootstrap {
+    ngDoBootstrap(appRef: ApplicationRef): void;
+}
+
 export interface DoCheck {
     ngDoCheck(): void;
 }