Typescript 枚举 扩展

enum_demo.ts

interface Enum {
  [id: number]: string
}

const getEnumKeys = (e: Enum) => {
  return Object.keys(e)
    .map(key => e[key])
    .filter(value => typeof value === 'string') as string[]
}

enum TrafficLight {
  red = 1,
  green = 2,
  yellow = 3,
}

namespace TrafficLight {
  export function keys() {
    return getEnumKeys(TrafficLight)
  }

  export function parse(light: Number): TrafficLight {
    return <TrafficLight>light
  }

  export function desc(light: TrafficLight) {
    switch (light) {
      case TrafficLight.green:
        return '绿灯'
      case TrafficLight.red:
        return '红灯'
      case TrafficLight.yellow:
        return '黄灯'

      default:
        return ''
      // 或者 throw new Error("参数错误")
    }
  }
}

console.error('emmmmmm')
console.log(TrafficLight.keys())
console.log(TrafficLight.desc(2))