How to cancel user upload in Formidable (Node.js)?

Question

I have been working on this problem for two days now, and I am stuck. I am using Node.js with Express, and I am trying to implement an upload form. Basically, I want the form to

Answer 1

Here is a solution that works for me using multiparty.

The answer given by jfizz does not work on all browsers.

VERY IMPORTANT: As josh3736 mentioned on a comment above, you MUST set the Connection header to close!

form.on('part', function(part) {
  if (![some condition I want to be met]) {
    form.emit('error', new Error('File upload canceled by the server.'));
    return;
  }
  ... code to handle the uploading process normally ...
});

form.on('error', function(err) {
  console.log('ERROR uploading the file:',err.message);
  res.header('Connection', 'close');
  res.status(400).send({ status:'error' });
  setTimeout(function() { res.end(); }, 500);
  next(err);
});