note.component.ts

export class AppComponent {
  note = new FormControl("");
  saveIndicator$ = of("Todas as mudanças foram salvas");
  saveCount = 0;

  ngOnInit() {
    const inputToSave$ = this.note.valueChanges.pipe(
      debounceTime(300),
      distinctUntilChanged(),
      share()
    );

    const savesInProgress$ = inputToSave$.pipe(
      mapTo(of("Salvando...")),
      tap(() => this.saveCount++),
    );

    const savesCompleted$ = inputToSave$.pipe(
      mergeMap(value => this.saveChanges(value)),
      tap(() => this.saveCount--),
    )

    inputToSave$.subscribe(console.log);
  }

  saveChanges(value: string) {
    return of(value).pipe(delay(1500));
  };
}