<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    <script type="text/javascript" src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/js/bootstrap.min.js"></script>
    <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" />
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/bootbox.js/4.4.0/bootbox.min.js"></script>
    <script type="text/javascript">
        function testAlert() {
            event.preventDefault();
            bootbox.alert({ size: "small", title: "Hello world!", message: "Your message here.", callback: function () { } });
        }
        function testeConfirm() {
            event.preventDefault();
            bootbox.confirm({ size: "small", message: "Are you sure to delete?", callback: function (confirmed) {
                if (confirmed) {
                    bootbox.alert("Successfully Deleted");
                } else {
                    bootbox.alert("Cancelled");
                }
            }
            });
        }
        function testePrompt() {
            event.preventDefault();
            bootbox.prompt({ size: "small", title: "What is your name?", callback: function (result) {
                if (result) {
                    bootbox.alert("Your Name is " + result)
                }
            }
            });
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <input type="submit" name="Button1" value="Alert" onclick="testAlert();" id="Button1" />
        <input type="submit" name="Button2" value="Confirm" onclick="testeConfirm();" id="Button2" />
        <input type="submit" name="Button3" value="Prompt" onclick="testePrompt();" id="Button3" />
    </div>
    </form>
</body>
</html>
This is work perfect.
 
But how can i connect this one with asp.net validation summary ?
I have done validation summary with validation. But i want to show in this alertbox.