title: Angular2 ngClass function not working as expected
body: <p>I have the following code</p>
  
  <pre><code>&lt;a *ngFor="let slipStatus of slipStatuses; class="item striped"
       [ngClass]="{
         'green background': slipStatus.status === 'SOLD',
         'yellow background': slipStatus.status === 'IN PROGRESS',
         'blue background': slipStatus.status === 'DONE'
       }"&gt;
  </code></pre>
  
  <p>I would expect that if any of the expressions are true, both classes would get added. However, the 'background' class only gets added for the <em>last</em> ngClass rule.</p>
  
  <p>So SOLD slips have class <code>green</code> only, IN PROGRESS have class <code>yellow</code> only and DONE slips correctly have both classes <code>blue background</code>.</p>
  
  <p>What's going on here?</p>