JSFiddle - React, Tailwind, and code Playground

HTML

<select>
    <option>sdfdsf</option>
    <option selected>sdfdsf</option>
    <option>sdfdsf</option>
</select>

<select>
    <option>sdfdsf</option>
    <option>sdfdsf</option>
    <option selected>sdfdsf</option>
</select>

<select>

</select>

JavaScript

$('select').each(function() {
  console.log(this.selectedIndex);
  console.log($(this).get(0).selectedIndex);
});