JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.21/themes/base/jquery-ui.css">
<a class="loginbtn" href="#">Login</a>

<div id="dialogwindow">
<p>Hello world</p>
</div>

JavaScript

$(function() {
    $( "#dialogwindow" ).dialog({
        height: 140,
        width: 400,
        zIndex: 999,
        autoOpen: false,
        modal: true
    });

    $( ".loginbtn" ).click(function() {
        $("#dialogwindow").dialog("open");
        return false;
    });
});