title: jQuery serialize() always empty
body: <p>I can't get this script working. Every time I send a file the script need to do one ajax request and send to server the file, but, serialize always send empty string.</p>
  
  <p>My Javascript</p>
  
  <pre><code>$('#upload-button input:file').change(function() {
      $('#upload-text').text('Sending file...');
  
      $.ajax({
          type: "GET",
          url: "?url=images/send",
          data: $('#image-upload').serialize(),
  
          success: function(response) {
              if(response.error) {
                  $('#upload-text').text(response.error);
              } else if(response.success) {
                  $('#upload-text').text('Image send');
              }
          },
      });
  })
  </code></pre>
  
  <p>My HTML</p>
  
  <pre><code>&lt;form name="image-upload" id="image-upload" action="?url=imagens/enviar" method="post" enctype="multipart/form-data"&gt;
      &lt;input type="file" name="selected-image" id="upload-hidden" value="" /&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>When I have selected a file, result from <code>alert($('#image-upload').serialize());</code>:</p>
  
  <pre><code>// EMPTY //
  </code></pre>
  
  <p>Result from <code>alert($('#image-upload input:file').attr('value'))</code>:</p>
  
  <pre><code>ponte-vecchio.jpg
  </code></pre>