JSFiddle - React, Tailwind, and code Playground
HTML
<select id="box1" onChange="myNewFunction(this.id, this.selectedIndex);" >
<option value="98">dog</option>
<option value="7122">cat</option>
<option value="142">bird</option>
</select>
JavaScript
myNewFunction = function(id, index) {
var selection = document.getElementById(id);
alert(selection.options[index].innerHTML);
};