JSFiddle - React, Tailwind, and code Playground

HTML

<select name="test">
    <option selected="selected">First</option>
    <option>Second</option>
    <option>Third</option>
    <option>Forth</option>
</select>

JavaScript

var sel = document.querySelectorAll('select[name="test"]')[4]; // Change this to target your select box
sel.selectedIndex = 1;