JSFiddle - React, Tailwind, and code Playground

HTML

<select>
    <option>Only Choice</option>
</select>
<select>
    <option>Choice A</option>
    <option>Choice B</option>
</select>

JavaScript

$("select").each(function(i, elem){
    if ($(this).children().length == 1) {
        this.outerHTML = "<span>"+this.innerHTML+"</span>";
    }
});