JSFiddle - React, Tailwind, and code Playground

by GopsAB

HTML

<select id="platypusDropDown">
    <option value="duckbill">duckbill</option>
    <option value="duckbillPlatypus">duckbillPlatypus</option>
    <option value="Platypus">Platypus</option>
    <option value="Platypi">Platypi</option>
</select>

<div id="addCategory">
    <input id="categoryInput" type="text" /> <br/>
    <input id="categoryInputAddBtn" type="button" value="Add new" />
</div>

CSS

#addCategory input
{
    width:196px;
}
select
{
    width:200px;
}

#addCategory
{
    display:none;
}

JavaScript

$('#platypusDropDown').click(function () {
   var myDiv = document.getElementById('addCategory');
    this.append(myDiv); 
});