title: ngClass in angular understanding syntax
body: <p>I am going through some code and I found a syntax like this :</p>
  
  <pre><code>&lt;div class="test" [ngClass]="{'active': isOverlay, 'on-page': onPage, 'spinner': showLoader, 'scroll': alphabetScroll}"&gt;
  </code></pre>
  
  <p>I am trying to understand what does this but I am not able to. What is all with the ngClass.
  Any help is much appreciated.</p>