title: Get data attribute for selected dropdown options
body: <p>I'm trying to post a custom data attribute on a select box option to a hidden form field.</p>
  
  <p>Here's my html:</p>
  
  <pre><code>&lt;select id="sampleorder" multiple="multiple"&gt;
   &lt;option value='xxx' data-amount='5'&gt;Name&lt;/OPTION&gt;
   &lt;option value='xxx' data-amount='15'&gt;Name&lt;/OPTION&gt;
   &lt;option value='xxx' data-amount='2'&gt;Name&lt;/OPTION&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>And jQuery</p>
  
  <pre><code>$('#submit_btn').click(function() {
    var options = $('select#sampleorder');    
    var samplesSelected = options.val();
  
    $('input[name=order]').val(samplesSelected);
    $('input[name=quantity]').val(sampleAmount);
  });  
  </code></pre>
  
  <p>I'm guessing that my variable "sampleAmount" should look somewhat like this</p>
  
  <pre><code>  var sampleAmount = options.val().data("amount");
  </code></pre>
  
  <p>But it's not giving me the expected results.
  What would be a good approach to get the data attribute value per item? </p>
  
  <p>Thanks!</p>