枚举类型可以将常用的常量字段使用enum关键字来定义

    1. enum Dirction{
    2.     Up="UP",
    3.     Down="DOWN",
    4.     Left="LEFT",
    5.     Right="RIGTH"
    6. }
    8. let dirc:Dirction = Dirction.Right
    10. if (dirc == Dirction.Right){
    11.     console.log('right',Dirction.Right)
    12. }