JSFiddle - React, Tailwind, and code Playground

HTML

<select id="select1">
     <option>I</option> 
     <option>Love</option>
     <option>my</option> 
    <option>granny</option>
</select>

JavaScript

var select1=document.getElementById("select1");
select1.onchange=function(){
var s=document.getElementById("select1").selectedIndex;
alert(s);
}