Java Script Alert ASP.Net C#

protected static class Alert
        {

            ///

            /// Shows a client-side JavaScript alert in the browser.
            ///

            /// The message to appear in the alert.
            public static void Show(string message)
            {
                // Cleans the message to allow single quotation marks
                string cleanMessage = message.Replace("'", "\\'");
                string script = "";

                // Gets the executing web page
                Page page = HttpContext.Current.CurrentHandler as Page;

                // Checks if the handler is a Page and that the script isn't allready on the Page
                if (page != null && !page.ClientScript.IsClientScriptBlockRegistered("alert"))
                {
                    page.ClientScript.RegisterClientScriptBlock(typeof(Alert), "alert", script);
                }
            }
        }

Demonstration: Alert.Show("This is alert massage..");