Adding the "Add a new City" button

Open the /ClientApp/src/app/cities/cities.component.html file and add the following code:

<!-- ... existing code ... -->

<h1>Cities</h1>

<p>Here's a list of cities: feel free to play with it.</p>

<p *ngIf="!cities"><em>Loading...</em></p>

<div class="commands text-right" *ngIf="cities">
  <button type="submit"
          [routerLink]="['/city']"
          class="btn btn-success">
      Add a new City
  </button>
</div>

<!-- ... existing code ... -->

Here we go. There's nothing new here; we've added the usual route-based button within a container and a *ngIf structural directive to make it appear after the cities array becomes available.