<form action="" method="post">
  
 <p>
  
 <input data-validation="even_number" type="text">
  
 </p>
  
 ...
  
 </form>
  
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
  
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery-form-validator/2.2.1/jquery.form-validator.min.js"></script>
  
<script>
  
 
  
// Add validation
  
$.formUtils.addValidator({
  
 name : 'even_number',
  
 validatorFunction : function(value, $el, config, language, $form) {
  
 return parseInt(value, 10) % 2 === 0;
  
 },
  
 errorMessage : 'You have to give an even number',
  
 errorMessageKey: 'badEvenNumber'
  
});
  
 
  
// Setup form validation
  
$.validate();
  
 
  
</script>