JSFiddle - React, Tailwind, and code Playground

HTML

<select id="select">
      <option>1</option>
      <option>2</option>
      <option>3</option>
    </select>
    <input id="textinput" type="text" />

JavaScript

console.log($('#select option:selected'));
    $('#select').change(function(){
        $('#textinput').val($(this).find('option:selected').attr('data-value'));
    });
    $('#textinput').keyup(function(){
        $('#select option:selected').attr('data-value', this.value);
    });