JSFiddle - React, Tailwind, and code Playground

HTML

<span id ="resolutionSpan">

    <select name="resolution" id="resolution" onchange="showValue();">
    <option value="0" selected >0</option>
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>     
    </select>

</span>

JavaScript

function showValue() {
    var e = document.getElementById("resolution");
    console.log( e.options[e.selectedIndex].value);
}