forms.ts

export class TestComponent {

  ngOnInit() {
    this.form = new FormGroup({...});
    this.valueChangesSubscription  = this.form.valueChanges.subscribe(console.log);
    this.statusChangesSubscription = this.form.statusChanges.subscribe(console.log);
  }

  ngOnDestroy() {
    this.valueChangesSubscription.unsubscribe();
    this.statusChangesSubscription.unsubscribe();
  }
}