@ Component ( { selector : 'app-button' , templateUrl : 'button.component.html' } ) export class ButtonComponent implements OnDestroy { private _focusIndicator : FocusIndicator ; constructor ( focusIndicatorService , elementRef ) { this . _focusIndicator = focusIndicatorService . monitor ( elementRef . nativeElement , { mouseFocusIndicator : true , touchFocusIndicator : true , keyboardFocusIndicator : true , programmaticFocusIndicator : true } ) ; } ngOnDestroy ( ) { this . _focusIndicator . destroy ( ) ; } }