所有可能的枚举值的打字稿类型

Question

So I know that keyof typeof <enum> returns a type of all possible keys of enum, such that given

enum Season{
 WINTER = 'winter',
 SPRING = 'spring',
 SUMMER = 'summer',
 AUTUMN = 'autumn',
}

let x: keyof typeof Season;

is equivalent to

let x: 'WINTER' | 'SPRING' | 'SUMMER' | 'AUTUMN';

my question is how do I get a type that will be equivalent to one of the possible values of the enum, for example:

let x: 'winter' | 'spring' | 'summer' | 'autumn';

Answer 1

Typescript doesn't allow this but as a workaround, we can make it with an object whose property values are string literals:

  const createLiteral = <V extends keyof any>(v: V) => v;
  const Season = {
   WINTER: createLiteral("winter"),
   SPRING: createLiteral("spring"),
   SUMMER: createLiteral("summer")
  }
  type Season = (typeof Season)[keyof typeof Season]
  const w: Season = "winter"; // works
  const x: Season = "sghjsghj"; // error

Hope this helps!!! Cheers!