我在TypeScript中定义了以下enum:

enum Color{
    Red, Green
}

现在在我的函数中,我以字符串的形式接收颜色。我尝试了以下代码:

var green= "Green";
var color : Color = <Color>green; // Error: can't convert string to enum

如何将该值转换为enum?


当前回答

试试这个

var color: color =(任何颜色)["绿色];

这对于3.5.3版本来说很好

其他回答

我需要知道如何循环枚举值(正在测试许多排列的几个enum),我发现这工作得很好:

export enum Environment {
    Prod = "http://asdf.com",
    Stage = "http://asdf1234.com",
    Test = "http://asdfasdf.example.com"
}

Object.keys(Environment).forEach((environmentKeyValue) => {
    const env = Environment[environmentKeyValue as keyof typeof Environment]
    // env is now equivalent to Environment.Prod, Environment.Stage, or Environment.Test
}

来源:https://blog.mikeski.net/development/javascript/typescript-enums-to-from-string/

这些答案对我来说都太复杂了……

您可以简单地在枚举上创建一个解析函数,期望其中一个键作为参数。添加新颜色时,不需要进行其他更改

enum Color { red, green}

// Get the keys 'red' | 'green' (but not 'parse')
type ColorKey = keyof Omit<typeof Color, 'parse'>;

namespace Color {
  export function parse(colorName: ColorKey ) {
    return Color[colorName];
  }
}

// The key 'red' exists as an enum so no warning is given
Color.parse('red');  // == Colors.red

// Without the 'any' cast you would get a compile-time warning
// Because 'foo' is not one of the keys in the enum
Color.parse('foo' as any); // == undefined

// Creates warning:
// "Argument of type '"bar"' is not assignable to parameter of type '"red" | "green"'"
Color.parse('bar');

如果您正在使用名称空间来扩展枚举的功能,那么您还可以这样做

    enum Color {
        Red, Green
    }

    export namespace Color {
      export function getInstance(color: string) : Color {
        if(color == 'Red') {
          return Color.Red;
        } else if (color == 'Green') {
          return Color.Green;
        }
      }
    }

像这样使用它

  Color.getInstance('Red');

试试这个

var color: color =(任何颜色)["绿色];

这对于3.5.3版本来说很好

简单的方法

enum Color { Red, Green }

const c1 = Color["Red"]
const redStr = "Red" // important: use `const`, not mutable `let`
const c2 = Color[redStr]

这既适用于数值枚举,也适用于字符串枚举。不需要使用类型断言。

未知enum字符串

Simple, unsafe variant
const redStrWide: string = "Red" // wide, unspecific typed string
const c3 = Color[redStrWide as keyof typeof Color]
Safe variant with checks
const isEnumName = <T>(str: string, _enum: T): str is Extract<keyof T, string> =>
    str in _enum
const enumFromName = <T>(name: string, _enum: T) => {
    if (!isEnumName(name, _enum)) throw Error() // here fail fast as an example
    return _enum[name]
}
const c4 = enumFromName(redStrWide, Color)

转换字符串enum值

字符串枚举没有反向映射(与数字枚举相反)。我们可以创建一个查找助手来将枚举值字符串转换为枚举类型:

enum ColorStr { Red = "red", Green = "green" }

const c5_by_name = ColorStr["Red"] // ✅ this works
const c5_by_value_error = ColorStr["red"] // ❌ , but this not

const enumFromValue = <T extends Record<string, string>>(val: string, _enum: T) => {
    const enumName = (Object.keys(_enum) as Array<keyof T>).find(k => _enum[k] === val)
    if (!enumName) throw Error() // here fail fast as an example
    return _enum[enumName]
}

const c5 = enumFromValue("red", ColorStr)

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