easyui datagrid生成序号列formatter

        {
          field: "index",
          title: "序号",
          halign: "center",
          align: "center",
          width: 80,
          formatter: function(value, row, index) {
            var options = $("#mainGrid").datagrid("options");
            return options.pageSize * (options.pageNumber - 1) + (index + 1);
          }
        },