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TypeScript - 枚举

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    Name
    Deng Hua
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目录

Introducing Enums

Enums allow us to define a set of named constants. We can give these constants numeric or string values. There's quite a few options when it comes to enums!

枚举允许我们定义一组命名常量。我们可以给这些常量数字或字符串值。要定义一个枚举类型，请使用enum关键字。

enum OrderStatus {
  PENDING, // (enum member) OrderStatus.PENDING = 0
  SHIPPED,
  DELIVERED,
  RETURNED,
}

const orderStatus = OrderStatus.DELIVERED

function isDelivered(status: OrderStatus) {
  return status === OrderStatus.DELIVERED
}

isDelivered函数的参数为一个枚举类型，它的枚举值可以在类型注释中找到。

创建枚举时，如果不指定任何值，typescript将会分配一个从0开始的数值。

当然，也可以手动为枚举值赋值。

enum OrderStatus {
  PENDING = 1,
  SHIPPED = 2,
  DELIVERED = 3,
  RETURNED = 4,
}

enum ArrowKey {
  UP = 'up',
  DOWN = 'down',
  LEFT = 'left',
  RIGHT = 'right',
}

混合类型枚举

enum HybridEnum {
  a = 1,
  b = 'string',
}