javascript - Ajax autocomplete Extender prevent to type invalid value in text box -

javascript - Ajax autocomplete Extender prevent to type invalid value in text box -

am using ajax autocompleteextender in asp textbox below.

it's working fine but, problem: when user type text invalid or not match database value, should show message user "keyword not matched..."

code

<asp:hiddenfield id ="hdnfieldvalue" runat="server"/> <asp:textbox id="txtcontactssearch" runat="server"></asp:textbox> <cc1:autocompleteextender servicemethod="searchcustomers" minimumprefixlength="2" completioninterval="100" onclientitemselected="clientitemselected" usecontextkey="true" enablecaching="false" completionsetcount="10" targetcontrolid="txtcontactssearch" id="autocompleteextender1" runat="server" firstrowselected = "false"> </cc1:autocompleteextender>

java script code

<script type="text/javascript"> function clientitemselected(sender, e) { $get(e.get_value()); $get("<%=hdnfieldvalue.clientid %>").value = e.get_value(); } </script>

i value using above javascript method asp hidden field. want set empty hidden field when user type invalid text

please give me suggestions.

thanks.

add in autoextender :

<cc1:autocompleteextender servicemethod="searchcustomers" onclientpopulated="clientpopulated" </cc1:autocompleteextender>

js : below can highlight text result,same way can check text

<script type="text/javascript"> function clientpopulated(source, args) { if (source._currentprefix != null) { var list = source.get_completionlist(); var search = source._currentprefix.tolowercase(); (var = 0; < list.childnodes.length; i++) { var text = list.childnodes[i].innerhtml; var index = text.tolowercase().indexof(search); if (index != -1) { var value = text.substring(0, index); </script>

javascript jquery asp.net ajaxcontroltoolkit