JSFiddle - React, Tailwind, and code Playground

HTML

<select>
    <option>item1</option>
    <option>item2</option>
    <option>item3</option>
    <option>item4</option>
    <option>item5</option>
</select>

JavaScript

var select = document.getElementsByTagName('select')[0];
select.selectedIndex = select.options.length-1;