console.log(rule);
                // rule = max18
                // rule = max120
                // rule = max6
                var pattMax = new RegExp('^(max).(\d{1,3})');

                pattMax.test(rule); //false?

                if(pattMax.test(rule)){
                    console.log('é max seguido de 1 á 3 digitos');
                }