JSFiddle - React, Tailwind, and code Playground

HTML

<select id="s1">
    <option>--</option><option selected="selected">1</option>
    <option>2</option>
    <option>3</option>
    <option>4</option>
</select>

JavaScript

setTimeout(function(){
    $('#s1').append("<option>NEW</option>");
},2000);