code: function() {
              var waitingOrConnected = connectionManager.getWaitingOrConnected(),
                  i;
  
              // ensure files are cancelled in reverse order which they were added
              // to avoid a flash of time where a queued file begins to upload before it is canceled
              if (waitingOrConnected.length) {
                  for (i = waitingOrConnected.length - 1; i >= 0; i--) {
                      controller.cancel(waitingOrConnected[i]);
                  }
              }
  
              connectionManager.reset();
          }
docs: Cancels all queued or in-progress uploads