How to reverse typing on a typescript enum?

Question

Given an enum in typescript

enum CoffeeSizes {
  Large = 'L',
  Medium = 'M',
  ExtraLarge = 'XL',
}

CoffeeSizes.Large === 'L' // true

How do I do the reverse lookup, where I can say

CoffeeSizes.L === 'Large'

How can I create a type with the inverse enum?

Do you want to infer the type from the existing enum, or re-define the enum? — skovy
– skovy, Commented Sep 17, 2019 at 3:15
Possible duplicate of TypeScript: Infer enum value type from enum type — gotnull
– gotnull, Commented Sep 17, 2019 at 3:33
@fuzz That link only grab values, I need an inverse enum with type. — user2167582
– user2167582, Commented Sep 17, 2019 at 3:45
Have a look here for a possible reverse mapping implementation. Reverse lookups are not possible for string enums. — ford04
– ford04, Commented Sep 17, 2019 at 9:42

Artem Bozhko · Accepted Answer · 2019-09-17 08:51:06Z

0

Reverse mappings are only possible for numeric non const enums.
As in the example below

enum CoffeeSizes {
  Large,
  Medium,
  ExtraLarge
}

const nameOffLargeCoffeeSize = CoffeeSizes[CoffeeSizes.Large];
CoffeeSizes[nameOffLargeCoffeeSize] === CoffeeSizes.Large;

You can get more details in TypeScript docs

answered Sep 17, 2019 at 8:51

Artem Bozhko

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