JSFiddle - React, Tailwind, and code Playground

HTML

<select id="carlist">
  <option value="volvo">Cars</option>
  <option value="saab">------------</option>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
  <option value="audi">Audi</option>
</select>

JavaScript

function sortlist()
{
    var cl = document.getElementById('carlist');
    var clTexts = new Array();

    for(i = 2; i < cl.length; i++)
    {
        clTexts[i-2] =
            cl.options[i].text.toUpperCase() + "," +
            cl.options[i].text + "," +
            cl.options[i].value;
    }

    clTexts.sort();

    for(i = 2; i < cl.length; i++)
    {
        var parts = clTexts[i-2].split(',');
        
        cl.options[i].text = parts[1];
        cl.options[i].value = parts[2];
    }
}

sortlist();