rxjs-btn-show-more-hide-btn.js

  private initSuggestionsMoreBtn(): void {
    Observable.fromEvent(this.moreSuggestionsBtn.nativeElement, 'click')
      .mapTo(this.stepSuggestions)
      .scan((acc, cur) => {
        return acc < this.suggestions.length ? acc + cur : this.initialLimitSuggestions;
      }, this.initialLimitSuggestions)
      .takeUntil(this.onDestroy$)
      .subscribe(
        res => {
          this.limitSuggestions = res;
          this.hasMoreSuggestions = (res < this.suggestions.length);
        },
        error => console.log('Error: ', error)
      );
  }