Dynamically create JavaScript alert & confirmation dialogs from server side C#

CreateJSAlertConfirm.cs

public static void CreateAlert(string key, string alertString)
{
    Page page = HttpContext.Current.Handler as Page;

    if (page != null)
    {
        if (!page.ClientScript.IsStartupScriptRegistered(key))
        {
            page.ClientScript.RegisterStartupScript(typeof(Page), key, "<script language=\"JavaScript\">alert(\"" + alertString + "\");</script>");
        }
    }
}

public static void CreateConfirm(System.Web.UI.WebControls.Button btn, string confirmString)
{
    btn.Attributes.Add("onclick", "return confirm(\"" + confirmString + "\");");
}