fromEvent

  @ViewChild('inputSearch') inputSearch: ElementRef;

  ngAfterViewInit(): void {
    fromEvent(this.inputSearch.nativeElement, 'keypress').pipe(
      map((el: KeyboardEvent) => el),
      debounceTime(500),
      distinctUntilChanged()
    ).subscribe((el2) => console.log(el2.target.value));
  }