JSFiddle - React, Tailwind, and code Playground

HTML

<select id="ddlList">
    <option value="1">Test</option>
    <option value="2">Test2</option>
    <option value="3">Test3</option>
   <input type="text" id="ts" name="fname">
</select>

JavaScript

var old;
var newV;

$("#ddlList").click(function() {
    old = this.value;
});

$("#ddlList").change(function() {
    newV = this.value;
    ts.value = newV;
    console.log(newV);
    console.log(old);
});