How to type an array to be sure that all posisble values are from an specific dict?-CodePudding

I'm looking some way to type the testArray to ensure that only keys from the dict example can be set in the array.

enum example {
    key1 = 'A',
    key2 = 2,
    key3 = '3',
};

const testArray: ?? = [example.key1, example.key2]; // Valid
const testArray: ?? = [example.key1, 'other']; // Invalid

I want ensure that only keys of example dict can be added to the testArray this way.

CodePudding user response：

You probably want something like this:

let example = {
  key1: 'A',
  key2: 2,
  key3: '3',
} as const;

type ExampleValueArray = typeof example[keyof typeof example][]

const testArray: ExampleValueArray = [example.key1, example.key2]; // Valid
const testArray2: ExampleValueArray = [example.key1, 'other']; // Invalid

Playground

CodePudding user response：

If you want that only the keys present in example to be present in an array you can use this

let example = {
  key1: 'A',
  key2: B,
  key3: '3',
};

export const testArray: (keyof typeof example)[];

Note that this will allow for multiple entries for key1, key2, etc.

If you want the values then you can use this

let example = {
  key1: 'A',
  key2: 'B',
  key3: '3',
} as const;

const a: ((typeof example)[keyof typeof example])[];