title: dropify image preview not show after change data-default-file attr using jquery
body: <p>I am using Dropify.js, and I want to edit some attr value using jquery.</p>
  
  <p>Here the HTML code:</p>
  
  <pre><code>&lt;input type="file" id="kk" class="dropify form-control" data-max-file-size="5M" data-default-file="" required /&gt;
  </code></pre>
  
  <p>then I try to change input element data-default-file attribute with:</p>
  
  <pre><code> $('#kk').attr({'data-default-file': '[[+photo]]',});
  </code></pre>
  
  <p>The attr value already change base on this allert</p>
  
  <pre><code> alert(document.getElementById("kk").getAttribute("data-default-file"));
  </code></pre>
  
  <p>In that way, I can see data-default-file but I can't see img on screen.</p>
  
  <p>when i using this html code, the img show on screen</p>
  
  <pre><code>&lt;input type="file" id="kk" class="dropify form-control" data-max-file-size="5M" data-default-file="[[+photo]]" required /&gt;
  </code></pre>
  
  <p>Can you tell me how can i fix it?</p>