Example of simple form made with vanialla React/Redux

ducks.js

const UPDATE_INPUT_VALUE = 'UPDATE_INPUT_VALUE';

export const changeField = (name, value) => ({
  type: UPDATE_INPUT_VALUE,
  name,
  value,
});

const defaultState = {
 firstname: 'test',
 lastname: 'test', 
}
export default (state = defaultState, action) => {       
  switch (action.type) {
    case UPDATE_INPUT_VALUE:          
      return {...state, [action.name]: action.value}
      
    default:
      return state;
  }
};

FormComponent.jsx

import React from 'react';
import PropTypes from 'prop-types';

const FormComponent = ({onChange, firstName, lastName}) =>
  <div>
    <input name="firstname" type="text" onChange={onChange} value={firstName} />
    <input name="lastname" type="text" onChange={onChange} value={lastName} />
  </div>;
      
FormComponent.propTypes = {
  onChange: PropTypes.func.isRequired,
  firstName: PropTypes.string.isRequired,
  lastName: PropTypes.string.isRequired,
};
  
export default FormComponent;

FormContainer.js

import {connect} from "react-redux";
import {changeField} from "../ducks";
import FormComponent from "../FormComponent";

export defualt connect(
    state => ({
      firstname: state.customer.firstname,
      lastname: state.customer.lastname,
    }),
    dispatch => ({
        onChange: event => dispatch(event.target.name, event.target.value),
    }),
)(FormComponent);