title: Dropzone.js - acceptedFiles from select box not working
body: <p>I want to be able to change the <code>acceptedFiles</code> option of a Dropzone element when the user changes the option they've selected from a <code>&lt;select&gt;</code> element. A bit like this code <code>Dropzone.options.myDropzone = { acceptedFiles: selected_value};</code></p>
  
  <p>So far I've tried two approaches:</p>
  
  <p>HTML select box:</p>
  
  <pre><code>&lt;select class="form-control" id="cond_file_type" name="cond_file_type"&gt;
      &lt;option&gt;-- File Type --&lt;/option&gt;
      &lt;option value="pdf"&gt;PDF&lt;/option&gt;
      &lt;option value="docx"&gt;DOCX&lt;/option&gt;
      &lt;option value="xlsx"&gt;XLSX&lt;/option&gt;
      &lt;option value="png"&gt;PNG&lt;/option&gt;
      &lt;option value="jpg"&gt;JPG&lt;/option&gt;
      &lt;option value="gif"&gt;GIF&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>Javascript:</p>
  
  <pre><code>// Attempt 1
  document.getElementById("cond_file_type").onchange = function(){
      var file_type = '.' + this.options[this.selectedIndex].value;
  
      Dropzone.options.myDropzone = {
          acceptedFiles: file_type,
      };
  };
  
  
  // Attempt 2
  var file_type = '';
  document.getElementById("cond_file_type").onchange = function () {
      file_type = '.' + this.options[this.selectedIndex].value;
  };
  Dropzone.options.myDropzone = {
      acceptedFiles: file_type,
  };
  </code></pre>
  
  <p>I tried 1 and 2 but neither of them worked.</p>