JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <select>
        <optgroup label="Some">
            <option id="opt1">1</option>
            <option id="opt2">2</option>
        </optgroup>
    </select>
    <input type="text" id="inputTest1" />
</body>

JavaScript

$(document).ready(function () {
    var showArea = $("#inputTest1");
    $('select').on('change', function () {
        // If you need the element that was selected
        console.log($(this).find('option:selected:first').text());
        
        // If you just need the value
        console.log($(this).val());
    });
});