title: jQuery Validate plugin not validating an element that's not a form input
body: <p>I need to validate with jQuery Validation Plugin a combobox component: <code>jqxComboBox</code>. This component is applied on a <code>div</code>. So defining </p>
  
  <pre><code>&lt;div id="component_id" /&gt;
  
  $( "#component_id" ).jqxComboBox({...});
  
  $("#component_id" ).rules( "add", {
      required: true,                  
      messages:{
          required: "Field is required"
      }
  });
  </code></pre>
  
  <p>throws the following exception: <code>Cannot read property 'nodeType' of undefined</code>. I think it should due to the fact that I'm applying validation rules on a div.</p>
  
  <p>This component generate an input type hidden to hold selected value. I have also tryed to apply validation rules on that hidden component, but this do not works: form is submitted also when hidden has no value.</p>
  
  <pre><code>$('input[type=hidden][name=myName]').rules( "add", {
      required: true,                  
      messages:{
          required: "Field is required"
      }
  });
  </code></pre>
  
  <p>Can someone please give me some hints on how to solve this?</p>