Is there a good way to generate types by importing all variables from a file in typescript

Question

I have a file with a lot of constant variables in it:

// foo.ts
export const FOO = 'foo';
export const BAR = 'bar';

I want to be able to declare a type that enforces that a value is one of those constants:

// fooTypes.ts
import * as consts from './foo';

const fooObjects = Object.values(consts);  // I don't want to declare this variable
export type FooConst = fooObjects[number]; // type ActivityType = "foo" | "bar"

This does what I want, FooConsts contains a union of all of the values from foo.ts, but I don't want to have to declare additional variables that will end up in my run-time/bundle. This is just for type checking.

// useFooTypes.ts
import { FooConst } from './fooTypes'

type FooHolder {
  value: FooConst;
}

Also, I don't want to repeat all those declarations in a union type.

I tried doing this in a declaration file, but alas, Statements are not allowed in ambient contexts.ts(1036)

Looking for this : https://stackoverflow.com/questions/56263200/how-to-define-string-literal-union-type-from-constants-in-typescript ? — Tushar Shahi, Oct 19 '22 at 19:43
It sounds like perhaps you want a TypeScript [enum](https://www.typescriptlang.org/docs/handbook/enums.html). — jfriend00, Oct 19 '22 at 20:09

score 1 · Answer 1 · answered Oct 19 '22 at 21:12

1

I ended up switching my implementation to use enum.

// foo.js
export type Foo = keyof typeof foo;

export enum foo {
  FOO = 'foo',
  BAR = 'bar'
}

answered Oct 19 '22 at 21:12

kvanost

11
2

Is there a good way to generate types by importing all variables from a file in typescript

1 Answers1

Linked