jquery - how to filter the null in jquery easyui datagrid

Question

i'm using datagrid and if client gets null data from server, like this: ret = "{'rows':[],'total':0}"; then the datagrid will send another http request to server. then use the loadFilter like this:

loadFilter: function (data) {
                //alert(JSON.stringify(data));
                if (data.rows == null) {
                    //alert('读取有问题，重新填充');
                    $(selector).datagrid("load");
                    return $(selector).datagrid("getData");
                }
                return data;
            }
but this doesn't catch the case i said. what's wrong?