检查 TypeScript 中的枚举中是否存在值 [英] Check if value exists in enum in TypeScript

问题描述

我收到一个数字 type = 3 并且必须检查它是否存在于这个枚举中:

I recieve a number type = 3 and have to check if it exists in this enum:

export const MESSAGE_TYPE = {
    INFO: 1,
    SUCCESS: 2,
    WARNING: 3,
    ERROR: 4,
};

我发现的最好方法是将所有枚举值作为数组获取并在其上使用 indexOf.但是生成的代码不是很清晰:

The best way I found is by getting all Enum Values as an array and using indexOf on it. But the resulting code isn't very legible:

if( -1 < _.values( MESSAGE_TYPE ).indexOf( _.toInteger( type ) ) ) {
    // do stuff ...
}

有没有更简单的方法来做到这一点?

Is there a simpler way of doing this?

推荐答案

如果你想让它与字符串枚举一起工作，你需要使用 Object.values(ENUM).includes(ENUM.value) 因为字符串枚举没有反向映射，根据 https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-4.html:

If you want this to work with string enums, you need to use Object.values(ENUM).includes(ENUM.value) because string enums are not reverse mapped, according to https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-4.html:

Enum Vehicle {
    Car = 'car',
    Bike = 'bike',
    Truck = 'truck'
}

变成:

{
    Car: 'car',
    Bike: 'bike',
    Truck: 'truck'
}

所以你只需要:

if (Object.values(Vehicle).includes('car')) {
    // Do stuff here
}

如果您收到以下错误:Property 'values' does not exist on type 'ObjectConstructor'，那么您的目标不是 ES2017.您可以使用此 tsconfig.json 配置:

If you get an error for: Property 'values' does not exist on type 'ObjectConstructor', then you are not targeting ES2017. You can either use this tsconfig.json config:

"compilerOptions": {
    "lib": ["es2017"]
}

或者你可以做任何演员:

Or you can just do an any cast:

if ((<any>Object).values(Vehicle).includes('car')) {
    // Do stuff here
}

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