母版页怎么使用javascript

母版页如何使用javascript？
母版页invoice_master：
<asp:Content   ID= "Content1 "   ContentPlaceHolderID= "ContentPlaceHolder1 "   Runat= "Server ">
        <script   language   = "javascript ">
                function   GetTotal()
                        {
                                docoment.all[ "tbxTotal "].value   =   docoment.all[ "tbxSubTotal1 "].value;
                        }
        </script>
       
        <div   style= "height:40px; ">
                <asp:textbox   runat= "server "   id= "tbxSubTotal1 "   onTextChanged= "GetTotal "> </asp:textbox> </div>
        <div> <asp:textbox   runat= "server "   id= "tbxTotal "   > </asp:textbox> </div>

</asp:content>

编译出错：
“GetTotal”不是“ASP.masterpages_invoice_master”的成员。


------解决方案--------------------------------------------------------
在page_load裡：
tbxSubTotal1.Attributes.Add( "onTextChanged ", "GetTotal() ");