lazyload2.directive.ts

export class LazyLoadDirective implements AfterViewInit, OnDestroy {
  private _url = '';

  @Input()
  set url(value: string) { // optional
    if (!this._url && value) { // url added runtime
      this.doRegister();
    }
    this._url = value;
  }

  public ngAfterViewInit() {
    if (!this._url) {
      // bypass the registration
    } else if (this.manual) { // register later
      const sub = this._service.announcedOrder.pipe(first()).subscribe(_ => this.doRegister());
      this._subscription.add(sub);
    } else { // register now (default)
      this.doRegister();
    }
  }