B/S is not like C/S. A MessageBox can pop up a prompt box. However, you can use js's "Alert" to pop up messages, or use some variant js methods. I would like to introduce you to the following categories. Four pop-up box codes: [csharp] protected void Message_Click (object sender, EventArgs e) {// The first Response. write ("<script language = javascript> alert ('first pop-up box '); </" + "script>"); // second Page. registerStartupScript ("", "<script language = 'javascript '> window. alert ('second pop-up box '); </script> "); // ClientScriptManager scriptManager = (Page) System. web. httpContext. current. handler ). clientScript; scriptManager. registerStartupScri Pt (typeof (string), "", "alert ('third pop-up box ');", true); // The fourth Page. clientScript. registerStartupScript (Page. getType (), "message", "<script language = 'javascript 'defer> alert ('Fourth pop-up box'); </script> ");} the above four methods are very simple. In fact, the simpler method is to encapsulate them into a method as follows. [Csharp] // the pop-up box public void Alert (string str_Message) {// The first Response. write ("<script language = javascript> alert ('first pop-up box '); </" + "script>"); // The second www.2cto.com Page. registerStartupScript ("", "<script language = 'javascript '> window. alert ('second pop-up box '); </script> "); // ClientScriptManager scriptManager = (Page) System. web. httpContext. current. handler ). clientScript; scriptManager. registerStartupScript (typeof (String), "", "alert ('third pop-up box ');", true); // The fourth Page. clientScript. registerStartupScript (Page. getType (), "message", "<script language = 'javascript 'defer> alert ('Fourth pop-up box'); </script> ");} when the usage frequency is relatively high, it is very convenient. You only need "Alert. Is it convenient? If you think it is good, just give it a try.