angular input eventemitter code example

Example 1: send event to child component angular

Parent-Component

eventsSubject: Subject<void> = new Subject<void>();

emitEventToChild() {
  this.eventsSubject.next();
}


Parent-HTML

<child [events]="eventsSubject.asObservable()"> </child>


Child-Component

private eventsSubscription: Subscription;

@Input() events: Observable<void>;

ngOnInit(){
  this.eventsSubscription = this.events.subscribe(() => doSomething());
}

ngOnDestroy() {
  this.eventsSubscription.unsubscribe();
}

Example 2: output event angular

@Component({...})
export class CounterComponent {

  @Input()
  count: number = 0;

  @Output()
  change: EventEmitter<number> = new EventEmitter<number>();

  increment() {
    this.count++;
    this.change.emit(this.count);
  }

  decrement() {
    this.count--;
    this.change.emit(this.count);
  }

  	// in parent component
	//(change)="countChange($event)"> 

}

Example 3: use of eventemitter in angular

@Component({
    selector : 'child',
    template : `
        <button (click)="sendNotification()">Notify my parent!</button>
    `
})
class Child {
    @Output() notifyParent: EventEmitter<any> = new EventEmitter();
    sendNotification() {
        this.notifyParent.emit('Some value to send to the parent');
    }
}

@Component({
    selector : 'parent',
    template : `
        <child (notifyParent)="getNotification($event)"></child>
    `
})
class Parent {
    getNotification(evt) {
        // Do something with the notification (evt) sent by the child!
    }
}