JSFiddle - React, Tailwind, and code Playground

HTML

<div id="selects">
<select name="folder1"></select>
<select name="folder2"></select>
<select name="folder3"></select>
</div>

JavaScript

if ($('#selects select[name="folder3"]').length) {
    return false;
} else {
    $('#selects').append('<select name="folder3"></select>');
}