title: difference between ng-class ternary operator and evaluating an expression
body: <p>I have expression 
  <code>ng-class="myVal &gt; 0 ? 'myClass' : 'none'"</code>, where <code>myVal</code> gets value after some ajax request in controller.</p>
  
  <p>The problem is, sometimes <code>myVal</code> gets new value in controller but the above class does not updated in the view.</p>
  
  <p>However, expression like <code>ng-class="{'myClass' : myVal &gt; 0}"</code> giving correct result everytime.</p>
  
  <p>What is the difference between the two? or should i use <code>ngClass</code> in different way?</p>