列舉

用於命名一組數值的型別：

數值預設為 0：

enum Day { Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday };
let bestDay: Day = Day.Saturday;

設定預設起始編號：

enum TenPlus { Ten = 10, Eleven, Twelve }

或指定值：

enum MyOddSet { Three = 3, Five = 5, Seven = 7, Nine = 9 }