@Component({
  selector: 'app-test',
  templateUrl: './test.component.html',
  styleUrls: ['./test.component.scss']
})
export class TestComponent implements OnDestroy {
  title = 'Hello World';
  showHistory = true;

  be2 = new BehaviorSubject(1);

  constructor(private heroService: HeroService) {
    this.heroService.mySubject.subscribe(v => console.log(v));
    interval(1000).subscribe(val => console.log(val));
  }

  toggle() {
    this.showHistory = !this.showHistory;
  }

  ngOnInit() {
    this.be2.pipe(
      map(v => v)
    ).subscribe(v => console.log(v));
  }

  ngOnDestroy() {
    console.log('fooo');
  }
}