<script language=javascript>
        function openDialogWin()
        {
            var result = window.showModalDialog("ShowMessage.aspx","","dialogHeight:160px; dialogWidth:300px; status:no; help:no; scroll:no");
            //window.show(ShowMessage.aspx, ,height=300, width=400, top=250, left=250, toolbar=no, menubar=no, scrollbars=no, resizable=no,location=no, status=no,_blank);
            if(result == "Yes")
                window.alert("You Clicked Yes!");
            else if(result == "No")
                window.alert("You Clicked No!");
            //document.writeln(result);
        }
    </script><input type=button value="按钮" name="btn" onclick="openDialogWin()" />            Response.Write("<script language=javascript>");
            Response.Write("function confirm(){ window.returnValue=Yes;window.close(); }");
            Response.Write("function cancel(){ window.returnValue=No;window.close(); }");
            Response.Write("</script>");
            Response.Write("<div align=center><input type=button value=Yes onclick=confirm() /><input type=button value=No onclick=cancel() /></div>");

http://www.cnblogs.com/maxianghui/archive/2006/09/18/507421.html