以下代码可用于在TypeScript中创建enum:

enum e {
    hello = 1,
    world = 2
};

这些值可以通过以下方式访问:

e.hello;
e.world;

我如何创建一个字符串值enum ?

enum e {
    hello = "hello", // error: cannot convert string to e
    world = "world"  // error 
};

当前回答

如果你想要的主要是易于调试(相当类型检查),不需要为枚举指定特殊值,这是我正在做的:

export type Enum = { [index: number]: string } & { [key: string]: number } | Object;

/**
 * inplace update
 * */
export function enum_only_string<E extends Enum>(e: E) {
  Object.keys(e)
    .filter(i => Number.isFinite(+i))
    .forEach(i => {
      const s = e[i];
      e[s] = s;
      delete e[i];
    });
}

enum AuthType {
  phone, email, sms, password
}
enum_only_string(AuthType);

如果您希望支持遗留代码/数据存储,则可以保留数字键。

这样,您就可以避免键入两次值。

其他回答

我也有同样的问题,然后想出了一个很好用的函数:

每个条目的键和值都是字符串,并且相同。 每个条目的值都是从键派生出来的。(即。“不要重复你自己”,不像字符串值的常规枚举) TypeScript类型成熟且正确。(防止拼写错误) 还有一种简单的方法可以让TS自动完成您的选项。(如。打字MyEnum。,并立即看到可用的选项) 还有其他一些优点。(见答案底部)

效用函数:

export function createStringEnum<T extends {[key: string]: 1}>(keysObj: T) {
    const optionsObj = {} as {
        [K in keyof T]: keyof T
        // alternative; gives narrower type for MyEnum.XXX
        //[K in keyof T]: K
    };
    const keys = Object.keys(keysObj) as Array<keyof T>;
    const values = keys; // could also check for string value-overrides on keysObj
    for (const key of keys) {
        optionsObj[key] = key;
    }
    return [optionsObj, values] as const;
}

用法:

// if the "Fruit_values" var isn't useful to you, just omit it
export const [Fruit, Fruit_values] = createStringEnum({
    apple: 1,
    pear: 1,
});
export type Fruit = keyof typeof Fruit; // "apple" | "pear"
//export type Fruit = typeof Fruit_values[number]; // alternative

// correct usage (with correct types)
let fruit1 = Fruit.apple; // fruit1 == "apple"
fruit1 = Fruit.pear; // assigning a new fruit also works
let fruit2 = Fruit_values[0]; // fruit2 == "apple"

// incorrect usage (should error)
let fruit3 = Fruit.tire; // errors
let fruit4: Fruit = "mirror"; // errors

现在有人可能会问,这个“基于字符串的enum”比只使用:

type Fruit = "apple" | "pear";

有几个优点:

Auto-complete is a bit nicer (imo). For example, if you type let fruit = Fruit., Typescript will immediately list the exact set of options available. With string literals, you need to define your type explicitly, eg. let fruit: Fruit = , and then press ctrl+space afterward. (and even that results in unrelated autocomplete options being shown below the valid ones) The TSDoc metadata/description for an option is carried over to the MyEnum.XXX fields! This is useful for providing additional information about the different options. For example: You can access the list of options at runtime (eg. Fruit_values, or manually with Object.values(Fruit)). With the type Fruit = ... approach, there is no built-in way to do this, which cuts off a number of use-cases. (for example, I use the runtime values for constructing json-schemas)

export enum PaymentType {
                Cash = 1,
                Credit = 2
            }
var paymentType = PaymentType[PaymentType.Cash];

我只是声明了一个接口,并使用该类型的变量访问枚举。保持接口和枚举同步实际上很容易,因为如果枚举中有什么变化,TypeScript会报错,就像这样。

typeof EAbFlagEnum类型的参数不可赋值 参数类型为“IAbFlagEnum”。属性“Move”类型缺失 “typeof EAbFlagEnum”。

这种方法的优点是在各种情况下使用enum(接口)不需要类型强制转换,因此支持更多类型的情况,例如switch/case。

// Declare a TypeScript enum using unique string 
//  (per hack mentioned by zjc0816)

enum EAbFlagEnum {
  None      = <any> "none",
  Select    = <any> "sel",
  Move      = <any> "mov",
  Edit      = <any> "edit",
  Sort      = <any> "sort",
  Clone     = <any> "clone"
}

// Create an interface that shadows the enum
//   and asserts that members are a type of any

interface IAbFlagEnum {
    None:   any;
    Select: any;
    Move:   any;
    Edit:   any;
    Sort:   any;
    Clone:  any;
}

// Export a variable of type interface that points to the enum

export var AbFlagEnum: IAbFlagEnum = EAbFlagEnum;

使用变量,而不是枚举,可以产生所需的结果。

var strVal: string = AbFlagEnum.Edit;

switch (strVal) {
  case AbFlagEnum.Edit:
    break;
  case AbFlagEnum.Move:
    break;
  case AbFlagEnum.Clone
}

标记是我的另一个需要,所以我创建了一个NPM模块,添加到这个例子中,并包括测试。

https://github.com/djabraham/ts-enum-tools

这里有一个相当干净的解决方案,它允许继承,使用TypeScript 2.0。我没有在早期的版本上尝试过。

附加条件:该值可以是任何类型!

export class Enum<T> {
  public constructor(public readonly value: T) {}
  public toString() {
    return this.value.toString();
  }
}

export class PrimaryColor extends Enum<string> {
  public static readonly Red = new Enum('#FF0000');
  public static readonly Green = new Enum('#00FF00');
  public static readonly Blue = new Enum('#0000FF');
}

export class Color extends PrimaryColor {
  public static readonly White = new Enum('#FFFFFF');
  public static readonly Black = new Enum('#000000');
}

// Usage:

console.log(PrimaryColor.Red);
// Output: Enum { value: '#FF0000' }
console.log(Color.Red); // inherited!
// Output: Enum { value: '#FF0000' }
console.log(Color.Red.value); // we have to call .value to get the value.
// Output: #FF0000
console.log(Color.Red.toString()); // toString() works too.
// Output: #FF0000

class Thing {
  color: Color;
}

let thing: Thing = {
  color: Color.Red,
};

switch (thing.color) {
  case Color.Red: // ...
  case Color.White: // ...
}

非常非常简单的Enum string (TypeScript 2.4)

import * from '../mylib'

export enum MESSAGES {
    ERROR_CHART_UNKNOWN,
    ERROR_2
}

export class Messages {
    public static get(id : MESSAGES){
        let message = ""
        switch (id) {
            case MESSAGES.ERROR_CHART_UNKNOWN :
                message = "The chart does not exist."
                break;
            case MESSAGES.ERROR_2 :
                message = "example."
                break;
        }
        return message
    }
}

function log(messageName:MESSAGES){
    console.log(Messages.get(messageName))
}