title: On specific button click add a class in ionic 3
body: <p>I have a situation where i have multiple records and i used in that <code>*ngFor</code> loop , so per record there is one button And I am trying to do is <code>onclick</code> change background of button so that it looks alike it is clicked</p>
  
  <pre><code>&lt;div class="main" *ngFor="let data of fetched_info; let i=index"&gt;
      &lt;ion-grid no-padding no-margin&gt;
          &lt;ion-row no-padding no-margin class="row"&gt;
              &lt;ion-col col-4 no-padding no-margin&gt; 
                  &lt;button ion-button small icon-start color="secondary"
  outline (click)="shortlist($event,data[i].username)" class=""&gt;
                      &lt;ion-icon ios="ios-star-outline" md="md-star-outline"&gt;&lt;/ion-icon&gt;
                      Shortlist
                  &lt;/button&gt;
              &lt;/ion-col&gt;
  
          &lt;/ion-row&gt;
      &lt;/ion-grid&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p><code>onclick</code> of <code>shortlist()</code> function i want to make it happen</p>