title: How to add background-image using ngStyle (angular2)?
body: <p>How to use ngStyle to add background-image?
  My code doesn't work:</p>
  
  <pre><code>this.photo = 'http://dl27.fotosklad.org.ua/20121020/6d0d7b1596285466e8bb06114a88c903.jpg';
  
  &lt;div [ngStyle]="{'background-image': url(' + photo + ')}"&gt;&lt;/div&gt;
  </code></pre>