scinote-web/app/views/comments/_edit.html.erb

<%= bootstrap_form_for(:comment, url: @update_url, remote: true, html: { method: :put, class: 'comment-form edit-comment-form' }, data: { role: 'edit-comment-message-form' }) do |f| %>
  <div class="form-group">
    <div class="input-group">
      <%= f.smart_text_area :message,
                            single_line: true,
                            autofocus: true,
                            hide_label: true,
                            data: { role: 'message-input', 'atwho-edit' => '' },
                            value: @comment.message %>
      <span class="input-group-btn">
        <a class="btn btn-default" data-action="save">
          <span class="fas fa-check"></span>
        </a>
      </span>
    </div>
    <span class="help-block hide"></span>
    <a data-action="cancel" href="#"><%= t('general.cancel') %></a>
  </div>
<% end %>