title: Cancelling submission while using jquery submit
body: <p>I'm submitting a form silently i.e without page refresh using jquery.submit() method. When user selects a file and click upload button upload starts and cancel button is enabled. But i don't know how to cancel this upload in between. Official jquery documentation says</p>
  
  <p><strong>"we can cancel the submit action by calling .preventDefault() on the event object or by returning false from our handler"</strong> ,but i didn't understand how to use this in my case. 
  Below is the code i'm using to submit the form.</p>
  
  <pre><code>$('#button').click(function() {
      $('#form').submit();
  });
  </code></pre>