JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="customComboBox">
&nbsp
<li>Test</li>
<li>Test 2</li>
<li>Test 3</li>

CSS

ul{
width: 50px;
height: 20px;
border: 1px solid black;
display: block;
}
li{
padding: 5px 0px;
width: 50px;
display: none;
}

JavaScript

$(document).ready(function(){
    $("#customComboBox").click(function(){
        $("li").toggle("slow");
    });
});