title: Showing a bootbox.js dialog to make a selection during dropzone.js form action while sending to node.js server
body: <p>I have a node.js/express site which has an upload dropbox which use dropzone.js to do drag and drop uploads. My dropzone inside my jade template looks like this currently: </p>
  
  <pre><code>div(id="dropzone")
  form(method="POST" action="/upload" class="dropzone" id="my-dropzone")
      div(class="dz-message")
          span Drop your zipped AgentCubes project here to upload it  
  </code></pre>
  
  <p>This currently works fine, but in the case where the user uploads the same file again I would like to provide the option to overwrite the old file or generate a new name for the duplicate upload. This would not work with my current scheme which simply sends the file /upload which is an express endpoint I have created which currently handles the upload. </p>
  
  <p>It is also complicated by the fact that I would need to post to the server to decide if the file is a duplciate upload, then show the bootbox.js dialog in the client and then finally send the upload data to the server. I have looked through the dropzone.js documentation but I can't seem to find anyway to accomplish this. How can this be done?</p>