Ajax File

addJSON (json) {

  let self = this;

  let formData = new FormData();
  
  formData.append('json', JSON.stringify(json));
  formData.append('file', avatar);

  let xhr = $.ajax({
    url:         'URL',
    method:      'METHOD',
    processData: false,
    contentType: false,
    data:        formData,
  });

  xhr.done((res, status, response) => {
    if (response.status == constants.OK_REQ) {
      let message = 'Los datos se guardaron correctamente';
      self.onMessage(message);
    } else if (response.status == constants.ACCEPTED_REQ) {
      self.onMessage(res.message);
    }
  });

  xhr.fail((res, status, respose) => {
    if (res.responseJSON) {
      let json = res.responseJSON;
      self.onMessage(json.message);
    } else {
      self.onMessage(constants.MESSAGE_ERROR);
    }
  });
  
}