title: Can a form submit be disabled if a HTML file input field is empty?
body: <p>In a form which contains only a</p>
  
  <pre><code>&lt;input id="fileInput" name="BugReport" type="file" /&gt;
  </code></pre>
  
  <p>input field, I would like to disable the Submit button if the file input is empty (no file was chosen yet). Is there a recommended way to do this? </p>