Text box auto complete based on other text box

function ace_allSearchCity() {
            var nam = '';
            var para = 'maincity' + '$' +
            document.getElementById('<%=hdnPropState.ClientID%>').value + '$' +
            document.getElementById('<%=txtPropCity.ClientID%>').value + '$' + nam;
            $find('<%=AutoCompleteExtenderPropCity.ClientID%>').set_contextKey(para);
        }


function ace_allSearchCityClear() {
            if (document.getElementById('<%=txtPropCity.ClientID%>').value == '') {
                document.getElementById('<%=hdnPropCity.ClientID%>').value = '';
            }
        }


function ace_PropCitySelected(sender, e) {
            document.getElementById('<%=hdnPropCity.ClientID%>').value = e._value;
        }


function ace_allSearchState() {
            var nam = '';
            var para = 'state' + '$' +
            document.getElementById('<%=txtPropState.ClientID%>').value + '$' +
            document.getElementById('<%=hdnPropCity.ClientID%>').value + '$' + nam;
            $find('<%=AutoCompletePropState.ClientID%>').set_contextKey(para);
        }

function ace_allSearchStateClear() {
            if (document.getElementById('<%=txtPropState.ClientID%>').value == '') {
                document.getElementById('<%=hdnPropState.ClientID%>').value = '';
            }
        }

function ace_PropStateSelected(sender, e) {
            document.getElementById('<%=hdnPropState.ClientID%>').value = e._value;
        }

<div>
                                            <div>
                                                State:
                                       <div>
                                                <asp:TextBox ID="txtPropState" runat="server" onfocus="ace_allSearchState();" onblur="ace_allSearchStateClear();"></asp:TextBox>
                                                <asp:AutoCompleteExtender ID="AutoCompletePropState" TargetControlID="txtPropState"
                                                    CompletionListCssClass="Completion_1" ServiceMethod="GetSearchAutodata" DelimiterCharacters=";,:/" ServicePath="~/GlobalSearch.asmx" MinimumPrefixLength="0" CompletionInterval="100"
EnableCaching="False" runat="server" Enabled="True" UseContextKey="True" OnClientItemSelected="ace_PropStateSelected">
                                                </asp:AutoCompleteExtender>
                                                <asp:HiddenField ID="hdnPropState" runat="server" />
                                            </div>
                                        </div>


<div>
                                            <div>
                                                City:
                                       <div>
                                                <asp:TextBox ID="txtPropCity" runat="server" OnTextChanged="txtPropCity_TextChanged"
                                                    onfocus="ace_allSearchCity();" onblur="ace_allSearchCityClear();"></asp:TextBox>
                                                <asp:AutoCompleteExtender ID="AutoCompleteExtenderPropCity" TargetControlID="txtPropCity"
                                                    CompletionListCssClass="Completion_1" ServiceMethod="GetSearchAutodata" DelimiterCharacters=";,:/" ServicePath="~/GlobalSearch.asmx" MinimumPrefixLength="0" CompletionInterval="100"
                                                    EnableCaching="False" runat="server" Enabled="True" UseContextKey="True" OnClientItemSelected="ace_PropCitySelected">
                                                </asp:AutoCompleteExtender>
                                                <asp:HiddenField ID="hdnPropCity" runat="server" />
                                            </div>
                                        </div>

[WebMethod]
        public string[] GetSearchAutodata(string prefixText, int count, string contextKey)
        {                      
            DataTable dtAdvSearch;

            string[] data = new string[11];
            
            if (contextKey == "null" || contextKey == null)
            {
                dtAdvSearch = GetLocation(prefixText.Trim(), "state", "");

            }
            else
            {
                data = contextKey.Split('$');

                dtAdvSearch = GetLocation(prefixText.Trim(), data[0], data[1]);


            }

            List<string> regions = new List<string>();
            if (dtAdvSearch.Rows.Count == 0 || dtAdvSearch.Select("Description<>''").Length == 0)
            {
                string[] msg = new string[] { "No Records Found" };
                return msg;
            }
            else
            {
                for (int i = 0; i < dtAdvSearch.Rows.Count; i++)
                {

                    var nam = AjaxControlToolkit.AutoCompleteExtender.CreateAutoCompleteItem(dtAdvSearch.Rows[i][1].ToString(), dtAdvSearch.Rows[i][0].ToString());
                    regions.Add(nam);
                }
                return regions.ToArray();
               }
        }