i'm using multer, multer-azure-storage, and blueimp-file-upload. all served from unpkg.com. below is a multiple file upload with the done trigger. working as of 10/22/17.
js file:
  <script src="https://unpkg.com/jquery@3.2.1/dist/jquery.min.js"></script>
  <script src="https://unpkg.com/blueimp-file-upload@9.19.1/js/vendor/jquery.ui.widget.js"></script>
  <script src="https://unpkg.com/blueimp-file-upload@9.19.1/js/jquery.iframe-transport.js"></script>
  <script src="https://unpkg.com/blueimp-file-upload@9.19.1/js/jquery.fileupload.js"></script>
page html, served from express:
          
      $('#fileupload').fileupload({
          url: 'https://domainwhatevs/my-listings/edit/[property id]/gallery',
          paramName: '_file',
          dataType: 'json',
          type: 'POST',
          autoUpload: true,
          add: function (e, data) {
              console.log('uploading:', data)
              data.submit();
          },
          done: function (e, data) {
              console.log('done triggered');
              console.log(data._response.result.result[0].originalname, 'uploaded at', data._response.result.result[0].url);
              $.each(data.files, function (index, file) {
                // console.log(file.name, 'uploaded.')
                // console.log('done');
                // console.log(index);
                // console.log(file);
              });
              console.log(data);
          }
      });
// GET /my-listings/edit/[property id]/gallery
app.get(
    [
        '/my-listings/edit/:_id/gallery'
    ],
    (req, res) => {
        console.log('image gallery:', req.params._id);
        res.render('my-listings--edit--gallery', {
            _id: req.params._id,
            session: req.session
        });
    }
);
// POST /my-listings/edit/[property id]/gallery
 app.post(
    [
        '/my-listings/edit/:_id/gallery'
    ],
    upload.array('_file'),
    (req, res, next) => {
        console.log(req.files);
        res.setHeader('Content-Type', 'application/json');
        res.send({result: req.files});
        next();
    }
);