Watcher Changes watcher Overview Execute code upon value change Example import {WatchDirective} from "./watch/watch.directive"; bootstrap(AppComponent, [ {provide: ng.PLATFORM_DIRECTIVES, useValue: WatchDirective, multi: true} ]); <h1>Watcher</h1> <input [(ngModel)]="watchData" value="Write here" [a2Watch]="watchData" (a2Change)="changeEvent = $event"> <br> changeEvent: {{changeEvent | json}}