upload.js

$(document).on('ready page:load', function () { new Dropzone("#dropzone", {
      autoProcessQueue: false,
      uploadMultiple: true,
      parallelUploads: 100,
      addRemoveLinks: true,
      maxFiles: 10,
      maxFilesize: 10,
      paramName: 'upload[document]',
      init: function() {
        var myDropzone = this;
        // First change the button to actually tell Dropzone to process the queue.
        $("#dropzone").submit(function(e) {
          // Make sure that the form isn't actually being sent.
          e.preventDefault();
          e.stopPropagation();
          myDropzone.processQueue();

        });
      },
      sendingMultiple: function(){
          // Gets triggered when the form is actually being sent.
          // Hide the success button or the complete form.
      },
      successmultiple: function(files, response) {
          $(files.previewElement).find('.dz-remove').attr('id', response.uploadId);
          $(files.previewElement).addClass('dz-success');
      },
      errormultiple: function(files, response) {
          // Gets triggered when there was an error sending the files.
          // Maybe show form again, and notify user of error
      },

      removedfile: function(file) {
        var id = $(file.previewTemplate).find('.dz-remove').attr('id');

        $.ajax({
          type: 'DELETE',
          url: '/uploads/' + id,
          success: function(data) {
            console.log(data.message);
          }
        });

        var previewElement;
        return (previewElement = file.previewElement) != null ? (previewElement.parentNode.removeChild(file.previewElement)) : (void 0);
      }
    });
  });