Update button workaround

index.html

<section>
  <!-- BUTTON -->
  <!-- add this where you would put the tag {{ 'Regenerate' | update_button: application.update_user_key_url }} -->
  <form action="{{ application.update_user_key_url }}" class="button_to js-regenerateButton" method="post">
    <div>
      <input name="_method" type="hidden" value="put">
      <input class="btn btn-danger btn-xs" type="submit" value="Regenerate">
    </div>
  </form>
  <!-- ENDBUTTON -->
  
</section>

<!-- add this script tag to the bottom of the page -->
<script>
  $(function () {
   var csrfToken = document.querySelector('meta[name=csrf-token]').content,
       formContent = document.querySelector('.js-regenerateButton > div'),
       inputCsrf = document.createElement('input');
    
    inputCsrf.type = 'hidden';
    inputCsrf.name = 'authenticity_token';
    inputCsrf.value = csrfToken;
    
    formContent.appendChild(inputCsrf);
  });
</script>