jQuery Validate an HTML5-Input-Pattern

<!DOCTYPE html>
<html>
  <head>
    <title></title>
    <script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
    <script src="https://raw.github.com/jzaefferer/jquery-validation/master/jquery.validate.js" type="text/javascript"></script>
    <script type="text/javascript">
    jQuery(function ($) {
      $.validator.addMethod(
        "pattern",
        function(value, element, regexp) {
          var re = new RegExp(regexp);
          return this.optional(element) || re.test(value);
        },
        "Please enter the required format."
      );
      // $.validator.messages.pattern = "Bitte das geforderte Format eingeben."; // i18n
      $('form').validate({onkeyup : function (element) {
        $(element).valid();
      }});
    });
    </script>
  </head>
  <body>
    <form action="#">
      <input type="text" name="moep" value="" placeholder="^[0-9]+$" required="required" pattern="^[0-9]+$"/>
      <button type="submit">Abschicken</button>
    </form>
  </body>
</html>