JSFiddle - React, Tailwind, and code Playground

HTML

<select name="testSelect">
   <optgroup label="fruits">
      <option value="apples">Apples</option>
      <option value="oranges">Oranges</option>
      <option value="pears">Pears</option>
   </optgroup>
   <optgroup label="cars">
      <option value="ford">ford</option>
      <option value="toyota">toyota</option>
      <option value="ferrari">ferrari</option>
   </optgroup>
</select>

JavaScript

$('select').change(function() {
    var selected = $(':selected', this);
    alert(selected.parent().attr('label'));
});