import { LoadingIndicator } from 'ng2-loading-indicator';

  @LoadingIndicator()
  tryLoadingIndicator() {
    return Observable.timer(3000).subscribe(x => {
      console.log('finished 3s');
    });
  }

  @LoadingIndicator()
  getDataFromApi() {
    return this.http.get('your-api.com')
    .map(res => res.json())
    .subscribe(res => {});
  }

@LoadingIndicator()
async tryLoadingIndicator() {
  await Observable.timer(3000).toPromise();
}

  @LoadingIndicator()
  tryLoadingIndicator() {
    return Observable.timer(3000).do(x => {
      console.log('finished 3s');
    });
  }

// Define a variable with HTMLElement
$div: Element; 

// Using ElementRef to get DOM element for this component
constructor(private elementRef: ElementRef) {}

// Set value for above variable (HTMLElement)
ngOnInit() {
    this.$div = this.elementRef.nativeElement.querySelector('div');
}

// Add the variable string list to @decorator
@LoadingIndicator(['$div'])
async trySectionLoading() {
  await Observable.timer(3000).toPromise();
}