JSFiddle - React, Tailwind, and code Playground

HTML

<select id="opt">
  <option value="a">a</option>
  <option value="b" selected="selected">b</option>
  <option value="c">c</option>
</select>

JavaScript

var opt = document.getElementById("opt");
var listLength = opt.options.length;
for(var i =0; i< listLength; i++) {
   if(opt.options[i].selected) {
      opt.options[i].textContent= 'the change HTML';
   }
}