JSFiddle - React, Tailwind, and code Playground

HTML

<select id="bar">
    <option value="bar1">bar1</option>
    <option value="bar2">bar2</option>
</select>
<span id="foo"></span>

JavaScript

function display_selected()
{
    $('#foo').text($('#bar').val());
}

setInterval(display_selected,100);