title: How to check isNumeric / isNumber in JSTL?
body: <p>How to do this simple check in JSTL (without extending any Java classes and additional JSP functions). I need it like this:</p>
  
  <pre><code>&lt;c:if test="${fn:isNumeric()}"&gt;
      // do something
  &lt;/c:if&gt;
  </code></pre>
  
  <p>Thanks in advance. </p>