JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.5/themes/smoothness/jquery-ui.css" />
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.5/jquery-ui.min.js" type="text/javascript"></script>
<body>
    <form runat="server">
        <div id="messageSentDialog" style="display:none">
            <p>ASP.NET button here</p>
        </div>
    </form>
</body>

JavaScript

$(function() {
    $("#messageSentDialog").dialog({
        bgiframe: true,
        autoOpen: false,
        draggable: false,
        resizable: false,
        modal: true,
        open: function(type, data) {
            $(this).parent().appendTo("form");
        },
        show: 'blind',
        buttons: {
            Ok: function() {
                $(this).dialog('close');
            }
        }
    });
});

function showMessageSentDialog() {
    $("#messageSentDialog").dialog("open");
}

$(function() {
    showMessageSentDialog();
});