How to get string value from react-datepicker 2.0.0 input?

Question

Struggling to get dates as strings from react-datepicker in React/Redux app. Back-end services operates with date fields as strings in format specific to front-end user language settings. Therefore it is easier to store dates as strings in Redux.

In pre 2.0.0 version react-datepicker operated with moment objects and conversion could be performed with momentDate.format().

Version 2.0.0 operates with vanilla JS dates. react-datepicker performs string <-> Date conversion with internal methods (formatDate) which are not exported. Could not manage to access these functions.

Currently using work-around performing conversion with moment.js. Approach has disadvantages:

• moment.js and react-datepicker format masks does not match (different letter cases for an example)
• extra library dependency (moment.js)

Current code:

import React from 'react';
import OriginalDatepicker from 'react-datepicker';
import moment from 'moment';

const dateFormat = 'dd.MM.yyyy'; // Depends on user current locale.
const momentDateFormat = dateFormat.toUpperCase();

function parseDate(dateString) {
  if (dateString) {
    return moment(dateString, momentDateFormat).toDate();
  } else {
    return null;
  }
}

function format(date) {
  if (date) {
    return moment(date).format(momentDateFormat);
  } else {
    return null;
  }
}

const ApplicationSpecificDatepicker = props => {
  if (props.hasOwnProperty('selectedString')) {
    const { selectedString, ...remaining } = props;
    props = { ...remaining, selected: parseDate(props.selectedString) };
  }
  const onChangeOverride = (...args) => {
    if (props.onChangeAsString) {
      const [date, ...remaining] = args;
      const stringDate = format(date);
      props.onChangeAsString(stringDate, ...remaining);
    }
    if (props.onChange) {
      props.onChange(...args);
    }
  }
  return (
    <OriginalDatepicker
      dateFormat={ dateFormat }
      { ...props }
      onChange={ onChangeOverride }
    />
  );
};

const DatepickerUsage = () => (
  <ApplicationSpecificDatepicker selectedString={ '31.12.2018' }
    onChangeAsString={ (date) => console.log(date) }
    />
);

What is recommended solution for accessing react-datepicker 2.0.0 input string values?