i am trying to pass the javascript variable value to hidden feild from code behind by onclientclick event.. i have button that have both client and server side onclick event

<asp:Button ID="btnSave" runat="server" Text="Save"  class="buttonstyle" 
                onclick="btnSave_Click" OnClientClick="otherdata()" />

i want to get the javascript value in codebehind from OnClientClick event and then want to insert that value to database table from Onclick event

  function otherdata() {

                var hv = $('input[id$=hdnOthers]').val();
                    var $arrT = $('#<%=gv_Others.ClientID %>').find('input:text[id$="txtEmp"]');
                    var count = [];
                    for (var i = 0; i < 10; i++) {
                        var $txt = $arrT[i];
                        count[i] = $($txt).val();

                    }
                    hv = count;
                    alert(hv);

            }

i am getting the value in alert and assigning the value to hidden field but problem is that i am not getting the value in hidden field from code behind.. although i have already pass the value to hidden field from javascript so why i am not getting that value from code behind..

protected void Insert_OtherServices()
    {
        dsJobCardTableAdapters.Select_OtherServiceTableAdapter dsother = new dsJobCardTableAdapters.Select_OtherServiceTableAdapter();

  string hdn = hdnOthers.Value;


        dsother.Insert_OtherService(hdn);

    }