title: How to check if a select option have the attribute "value"?
body: <p>I have a <code>select</code> like this:</p>
  
  <pre><code>&lt;select id="select-filter-item" data-hasqtip="3" oldtitle="Seleziona un tipo di servizio e filtra gli appuntamenti visualizzati sul calendario." title="" aria-describedby="qtip-3"&gt;
      &lt;optgroup label="Servizi" type="services-group"&gt;
          &lt;option type="provider"&gt;Tutti i trattamenti&lt;/option&gt;
          &lt;option value="5CFCA63F-5550-4F18-9C03-FC5B50FC67CC" type="service"&gt;Taglio capelli &lt;/option&gt;
          &lt;option value="B626AD6A-E59B-4D7A-875B-CE3389B11E69" type="service"&gt;Colore capelli&lt;/option&gt;
          &lt;option value="93003E75-A757-43F0-B2E8-C5ACDD57DBB3" type="service"&gt;Trattamenti viso&lt;/option&gt;
          &lt;option value="3E9924C3-6AEB-4450-B534-C06DC30F9E35" type="service"&gt;Massaggi corpo&lt;/option&gt;
      &lt;/optgroup&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>I need to determine if the selected option has the attribute <code>value</code>. For example, the first option "<em>Tutti i trattamenti</em>" doesn't have any value attribute. How can I implement this in jQuery?</p>