jQuery Grid Plugin - jqGrid

<script type="text/javascript">
        $(document).ready(function() {
            jQuery("#grillausers").jqGrid({
                url: 'FetchDatos.aspx',
                datatype: 'json',
                colNames: ['ID', 'Nombre', 'Activo', 'Sexo'],
                colModel: [
                { name: 'Id', index: 'Id', width: 20, editable: false, editoptions: { readonly: true, size: 5} },
                { name: 'Nombre', index: 'Nombre', width: 250, align: "left", editable: true, size: 100 },
                { name: 'IsClosed', index: 'IsClosed', width: 200, align: 'left', editable: true, edittype: "checkbox", editoptions: { value: "Activo:Inactivo", formatter: "checkbox"} },
                { name: 'Gender', index: 'Gender', width: 200, formatter: 'select', editable: true, edittype: "select", editoptions: { value: "0:select;1:Masculino;2:Femenino"} }
            ],
                rowNum: 10,
                rowList: [5, 10, 15, 20],
                pager: '#paginaciongrilla',
                sortname: 'Id',
                viewrecords: true,
                sortorder: "desc",
                jsonReader: {
                    repeatitems: false
                },
                caption: 'Usuarios',
                height: '100%',
                editurl: 'FetchDatos.aspx'
            });
            jQuery("#grillausers").jqGrid('navGrid', '#paginaciongrilla', { edit: false, add: false, del: false, search: false });

            jQuery("#a1").click(function() {
            var id = jQuery("#paginaciongrilla").jqGrid('getGridParam', 'selrow');
alert(id);
                if (id) {
                                    var ret = jQuery("#paginaciongrilla").jqGrid('getRowData', id);
                                        alert("id=" + ret.id + "!");
                } else {
                    alert("No tomo nada...");
                }
            });

            // Accordion
            $("#accordion").accordion({ header: "h3" });

            // Tabs
            $('#tabs').tabs();

        });
        </script>