ClientScript.RegisterClientScriptBlock alerts gives Microsoft JScript runtime error

Hi,

Here I have created sample.Please check if your selectbox is undefined of null while passing to addOption Method.

HTML

<div>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
    <script type="text/javascript">
        $(function () {
            fillstates();
        });
        function addOption(selectbox, text, value) {
            var optn = document.createElement("OPTION");
            text = text.replace(/&amp;/g, '&');
            value = value.replace(/&amp;/g, '&');
            optn.text = text;
            optn.value = value;
            selectbox.options.add(optn);
        }

        function fillstates() {
            var stateArray = document.getElementById('<%=hdnSateNames.ClientID %>').value.split("#");
            for (var count = 0; count <= stateArray.length - 1; count++) {
                var state = stateArray[count];
                var stateCode = (state.split(";")[0]);
                var StateName = (state.split(";")[1]);
                addOption(document.getElementById('<%=BMO_ddlMortgagorState.ClientID%>'), StateName, stateCode);
            }
        }
    </script>
        
    <asp:HiddenField ID="hdnSateNames" Value="01;Maharashtra#02;Goa" runat="server" />
    <asp:DropDownList ID="BMO_ddlMortgagorState" runat="server">
    </asp:DropDownList>
</div>

Screenshot