import React from "react";
import ReactDOM from "react-dom";
import { Formik, Form, Field, FieldArray } from "formik";

function App() {
  //------ Функция, которая получает values ----------
  const getValues = values => console.log(values.fields[0]);
  //----------------------
  return (
    <>
      <Formik
        initialValues={{ fields: [""] }}
        onSubmit={(values, actions) => {
          actions.setSubmitting(false);
          console.log(values);
          return false;
        }}
        render={({ setFieldValue, values }) => (
          <Form>
            <FieldArray
              name="fields"
              render={() => (
                <Field
                  type="text"
                  name="fields.0"
                  placeholder="Write something"
                  onChange={e => {
                    setFieldValue("fields.0", e.target.value);

                    //---------------
                    getValues(values);
                    //---------------

                  }}
                />
              )}
            />
          </Form>
        )}
      />
    </>
  );
}

ReactDOM.render(<App />, document.getElementById("root"));