JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.0/themes/south-street/jquery-ui.css">
<body>

</body>

JavaScript

var message = "Please provide Phone number."
var phoneNum = "<input type='text' id='phoneNum' name='phoneNum'/> ";
var dialogHtml = "<div id='confirmPhoneNumber'>" + message + phoneNum + "<div id='dialogError' style='display:none'>Phone number field cannot be empty</div>" + "</div>";
$('body').append(dialogHtml);
$("#confirmPhoneNumber").css("font-size", "70%");
$("#confirmPhoneNumber").dialog({
    autoOpen: true,
    resizable: false,
    modal: true,
    title: 'Save Phone',
    buttons: {
        'Save': function() {
            // Phone number must be provided
            if ($("#phoneNum").val().trim().length == 0) {
                $("#dialogError").show();
            } else {
                alert('Got a number');
            }
        },
        'Cancel': function() {
            $(this).dialog('close');
        }
    }
});