parseFormData(formData) {
    const setData = {
      xml: formData => parseXML(formData),
      json: formData => window.JSON.parse(formData),
    }
    if (typeof formData !== 'object') {
      formData = setData[this.options.dataType](formData) || false
    }
    return formData
  }
ensure formData is correct type
@param {Object|string} formData
@return {Object} formData