JSFiddle - React, Tailwind, and code Playground

HTML

<select id="treatmentGroupDropDown">
    <option value="1">1</option>
</select>

JavaScript

$("#treatmentGroupDropDown").bind('itemAdded', function (event, item) { alert('item added: ' +$(item).val()); });

var option = new Option("Test", "Test")
$("#treatmentGroupDropDown").append(option);
$('#treatmentGroupDropDown').trigger('itemAdded', option);