title: Display i18n message on button.onclick attribute
body: <p>How should I display a Thymeleaf i18n messages on the code below:</p>
  
  <pre><code>&lt;button th:text="#{msg_warning}" onclick="return confirm("[[#{msg_confirm_warning}]]")"&gt;
      Delete
  &lt;/button&gt;
  </code></pre>
  
  <p>Even using <code>th:attr</code></p>
  
  <pre><code>&lt;button th:text="#{msg_warning}" th:attr="onclick='return confirm(\'#{msg_confirm_warning}\');'"&gt;
      Delete
  &lt;/button&gt;
  </code></pre>
  
  <p>The output should be the string value of <code>msg_confirm_warning</code> whenever the button is clicked. But it displays <code>[[#{msg_confirm_warning}]]</code> string instead.</p>