easyui datagrid 键盘上下控制选中行

$.extend($.fn.datagrid.methods, {
    keyCtr : function (jq) {
        return jq.each(function () {
            var grid = $(this);
            grid.datagrid(‘getPanel‘).panel(‘panel‘).attr(‘tabindex‘, 1).bind(‘keydown‘, function (e) {
                switch (e.keyCode) {
                case 38: // up
                    var selected = grid.datagrid(‘getSelected‘);
                    if (selected) {
                        var index = grid.datagrid(‘getRowIndex‘, selected);
                        grid.datagrid(‘selectRow‘, index - 1);
                    } else {
                        var rows = grid.datagrid(‘getRows‘);
                        grid.datagrid(‘selectRow‘, rows.length - 1);
                    }
                    break;
                case 40: // down
                    var selected = grid.datagrid(‘getSelected‘);
                    if (selected) {
                        var index = grid.datagrid(‘getRowIndex‘, selected);
                        grid.datagrid(‘selectRow‘, index + 1);
                    } else {
                        grid.datagrid(‘selectRow‘, 0);
                    }
                    break;
                }
            });
        });
    }
});

$("#id").datagrid({}).datagrid("keyCtr");