https://stackoverflow.com/questions/9720143/asp-net-web-application-message-box
Or create a method like this in your solution:
public static class MessageBox { public static void Show(this Page Page, String Message) { Page.ClientScript.RegisterStartupScript( Page.GetType(), "MessageBox", "<script language='javascript'>alert('" + Message + "');</script>" ); } }
Then you can use it like:
MessageBox.Show("Here is my message");
public static void PageAlert(Page objPage, string strContent) { objPage.ClientScript.RegisterClientScriptBlock(objPage.GetType(), "alert", "<script type='text/javascript'>window.alert('" + strContent + "');</script>"); }