CODEWITHSUNDEEP
typescript
basickarl
basickarl

Reputation: 40522

How to inject Enums in TypeScript?

How to inject Enums in TypeScript? Is this possible and recommended?

enums.ts:

export enum Environment {
    Development = 'Development',
    Production = 'Production',
    Test = 'Test'
}

file:

import { Environment as _Environment } from '../enums';
function myfunc(Environment: Environment = _Environment): void {}

I get:

application/libs/config/index.ts:23:18 - error TS2749: 'Environment' refers to a value, but is being used as a type here.

23     Environment: Environment = _Environment

Upvotes: 1

Views: 557

Answers (3)

Maciej Sikora
Maciej Sikora

Reputation: 20162

Enum is kind of union/variant type. It means that it defines group of possible values, but is not a value itself. Your function has an argument of type Environment, and it means that you can assign one of possible value existing in the enum Enviroment, but not Enum itself as you try to do, as Enviroment itself is not a value but a type.

function myfunc(Environment: Environment = _Environment.Production ): void {}

As you can see I am choosing arbitrarily one from possible values in the Enum.

You can look on Enums like on unions with static structural representation. It means that:

type T = 'a' | 'b';
enum TEnum {
  a = 'a'
  b = 'b'
}

// using
const a: T = 'a' // direct setting the value
const b: TEnum = TEnum.b // using existing enum structure to set the value

Upvotes: 0

ErBu
ErBu

Reputation: 383

This is how you would do it. Default envoronment being Development.

export enum Environment {
    Development = 'Development',
    Production = 'Production',
    Test = 'Test'
}

function myfunc(e: Environment = Environment.Development): void {}

Upvotes: 0

Bohdan Stupak
Bohdan Stupak

Reputation: 1593

This works fine

function myfunc(Environment: _Environment): void {}

However, if you want to utilize default parameters you can try something like this

function myfunc(Environment: _Environment = _Environment.Development): void {}

Upvotes: 1

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