JSFiddle - React, Tailwind, and code Playground

HTML

<select>
    <optgroup label="NFC EAST">
        <option value="DallasCowboys">Dallas Cowboys</option>
        <option value="NewYorkGiants">New York Giants</option>
        <option value="PhiladelphiaEagles">Philadelphia Eagles</option>
        <option value="WashingtonRedskins">Washington Redskins</option>
    </optgroup>
    <optgroup label="NFC NORTH">
        <option value="ChicagoBears">Chicago Bears</option>
        <option value="DetroitLions">Detroit Lions</option>
        <option value="GreenBayPackers">Green Bay Packers</option>
        <option value="MinnesotaVikings">Minnesota Vikings</option>
    </optgroup>
</select>
<button id="next">Next</button>
<button id="prev">Previous</button>

JavaScript

$('#next').on('click', function () {
    var value = $('select option:selected').next('option').val() || $('select option:selected').parent().next().children('option').first().val();
    if (value) $('select').val(value);
});

$('#prev').on('click', function () {
    var value = $('select option:selected').prev('option').val() || $('select option:selected').parent().prev().children('option').last().val();
    if (value) $('select').val(value);
});