JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<body>

<form>
<select id="mySelect" size="8" style="width:100px">

</select>
</form>
<br>

<p>Click the button to add a "Kiwi" option at the end of the dropdown list.</p>

<button type="button" onclick="myFunction()">Insert option</button>

<script>
    document.getElementById("mySelect").setAttribute('disabled', true);
function myFunction()
{document.getElementById("mySelect").removeAttribute('disabled');
var x = document.getElementById("mySelect");
var option = document.createElement("option");
option.text = "Kiwi";
x.add(option);
}
</script>

</body>
</html>