title: Angular 2 simple directive to toggle class
body: <p>I have structure in html like this</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div class="col-8"&gt;
      text
  &lt;/div&gt;
  &lt;div class="col-4"&gt;
      text
  &lt;/div&gt;
  </code></pre>
  
  <p>What I need is to create simple directive in my <strong>app.component.ts</strong>, that will on click on some element toggle and ad class <strong>col-12</strong>, than html will look like this</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div class="col-8 col-12"&gt;
      text
  &lt;/div&gt;
  &lt;div class="col-4 col-12"&gt;
      text
  &lt;/div&gt;
  </code></pre>
  
  <p>I am sorry i dont have nothing in code right now, but i need help to get started</p>