local.put(mileageDoc).then(function (response) {
  return Promise.all(storedFiles.map(function(storedFile) {
    return local.putAttachment(response.id, storedFile.name, response.rev, storedFile, storedFile.type);
  }));
}).then(function () {
  console.log('done');
}).catch(function (err) {
  console.log('error', err);
});