title: Dynamic refresh background-image with ngStyle In AngularJs
body: <p>When i use Angular to <strong>dynamic change div 's backgroundImage</strong>, i find there are two ways to set backgrond-image:</p>
  
  <p><strong>first:</strong></p>
  
  <p><code>&lt;div style="background:url({{example_expression}})"&gt;&lt;/div&gt;</code></p>
  
  <p><strong>the second:</strong></p>
  
  <p><code>&lt;div ng-style="{backgroundImage: 'url({{example_expression}})'}"&gt;&lt;/div&gt;</code></p>
  
  <p>But when i change <code>example_expression</code>, only the first way can dynamically change the backgroundImage.</p>
  
  <p>There is a example in <a href="http://plnkr.co/edit/iss7x1KlNvRemdIUGzZ1?p=preview" rel="noreferrer">Plunker</a></p>
  
  <p><strong>What's wrong with ngStyle?</strong> </p>