title: jQuery UI Sortable - pass additional data with serialize
body: <p>In the below code, I also want to pass the value <code>listing_id</code> in my AJAX post:</p>
  
  <pre><code>$('#listing .images').sortable({
      tolerance: 'pointer',
      update: function(event, ui){
          var data = $(this).sortable('serialize');
          var listing_id = $('#listing').attr('data-id');
  
          $.ajax({
              type: 'post',
              dataType: 'json',
              url: 'listings/sortimages',
              data: data,
              success: function(result){
                  alert('Successfully re-ordered items.');
              }
          });
      }
  });
  </code></pre>
  
  <p>I have tried:</p>
  
  <p><code>data.push({name: 'listing_id', value: listing_id});</code></p>
  
  <p>It says <code>data.push is not a function</code>.</p>