downgradeComponent

A helper function that allows an Angular component to be used from AngularJS.

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Description

Part of the upgrade/static library for hybrid upgrade apps that support AOT compilation

This helper function returns a factory function to be used for registering an AngularJS wrapper directive for "downgrading" an Angular component.

Usage notes

Examples

Let's assume that you have an Angular component called ng2Heroes that needs to be made available in AngularJS templates.

// This Angular component will be "downgraded" to be used in AngularJS
@Component({
  selector: 'ng2-heroes',
  // This template uses the upgraded `ng1-hero` component
  // Note that because its element is compiled by Angular we must use camelCased attribute names
  template: `<header><ng-content selector="h1"></ng-content></header>
             <ng-content selector=".extra"></ng-content>
             <div *ngFor="let hero of heroes">
               <ng1-hero [hero]="hero" (onRemove)="removeHero.emit(hero)"><strong>Super Hero</strong></ng1-hero>
             </div>
             <button (click)="addHero.emit()">Add Hero</button>`,
})
export class Ng2HeroesComponent {
  @Input() heroes!: Hero[];
  @Output() addHero = new EventEmitter();
  @Output() removeHero = new EventEmitter();
}

We must create an AngularJS directive that will make this Angular component available inside AngularJS templates. The downgradeComponent() function returns a factory function that we can use to define the AngularJS directive that wraps the "downgraded" component.

// This directive will act as the interface to the "downgraded" Angular component
ng1AppModule.directive('ng2Heroes', downgradeComponent({component: Ng2HeroesComponent}));

For more details and examples on downgrading Angular components to AngularJS components please visit the Upgrade guide.