Enterkey textbox button clicked is not working firefox

<script type="text/javascript">
            $('#myDiv').keydown(function (e) {
                if ((e.which == 13) || (e.which == keyCode.ENTER)) {
                    alert("enter pressed");
                    //$('#btnSaveAU').trigger('click');
                }
            })
</script>

<div id="myDiv" runat="server">
                 <asp:TextBox ID="txtAuthorisedPwd" Width = "150px" TextMode="Password" Height="18px"   runat="server"></asp:TextBox>
                 <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtAuthorisedPwd"
                  ErrorMessage="Password is required." ToolTip="Password is required."
                  ValidationGroup="SaveAU">*</asp:RequiredFieldValidator>
                         </div>