title: jquery selector on multiple id
body: <p>Hi have a html code like this</p>
  
  <pre><code>&lt;input type="text" value="quantita" id="quantita" name="quantita"&gt;
  &lt;input type="text" value="prodotto" id="prodotto" name="prodotto"&gt;
  &lt;input type="text" value="prezzo" id="prezzo" name="prezzo"&gt;
  </code></pre>
  
  <p>Now I'm trying to do a jquery code that add a button if the value of all these id is different from NULL</p>
  
  <p>so I do this</p>
  
  <pre><code>var list = $("#prezzo", "#quantita", "#prodotto").val();
  if (list!="")
  {...do this...}
  else
  {....do nothing...}
  </code></pre>
  
  <p>but it doesn't work</p>