00005.显示时刻

https://qiita.com/karintou/items/04a279a92f2055ee07a1
TS:

import { Observable} from 'rxjs';
private now: Observable<Date>;
private intervalList: any[] = [];
constructor() { // ngOnInit()
    this.now = new Observable((observer) => {   
      this.intervalList.push(
        setInterval(() => {
          observer.next(new Date());
        }, 1000)
      );
    });
}

ngOnDestroy() {
    if (this.intervalList) {
      this.intervalList.forEach((interval) => {
        clearInterval(interval);
      });
    }
}

HTML：

{{ now | async | date:'HH:mm:ss' }}