title: How I know if my input type="file" has content selected
body: <p>i have a simple input file <code>&lt;input type="file" name="file" id="file"&gt;</code>
  but I'm trying to validate after the post if the input file has content.</p>
  
  <p>I trying with <code>$("#file").val()</code> but, the dom of the controls is the same always.</p>