title: font-awesome icon doesn't show up in [ngClass] in Angular 4
body: <p>I'm facing a strange error in my Angular 4 HTML Template, I'm trying to toggle the class of <code>&lt;i&gt;</code> tag, but only one class shows up, but not the other. Here is my code;</p>
  <pre><code>&lt;i [ngClass]=&quot;{'fa fa-eye': visible, 'fa fa-eye-slash': !visible}&quot; aria-hidden=&quot;true&quot; (click) = &quot;toggle(pass)&quot;&gt;&lt;/i&gt;
  </code></pre>
  <p>TS:</p>
  <pre><code>visible = false;
  toggle(event){
      this.visible = !this.visible;
  }
  </code></pre>
  <p>When i check my app, the first icon shows up i.e. the default on <code>fa fa-eye-slash</code> but when i click on it it shows only box.</p>
  <p><a href="https://i.stack.imgur.com/RgKNE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RgKNE.png" alt="HTML:" /></a>
  <a href="https://i.stack.imgur.com/fOZ7a.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fOZ7a.png" alt="enter image description here" /></a></p>
  <p><strong>Edit:</strong></p>
  <p>Tried with different icons from FA, but nothing shows up.</p>