Created
August 13, 2024 15:17
-
-
Save AriPerkkio/fae064b20778c6a4a54a36416a127486 to your computer and use it in GitHub Desktop.
UnionToArray TS
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| /** | |
| * Create an array of string literal where all types are required and allowed just once | |
| * | |
| * ```ts | |
| * // Example usage: Make sure test.each() covers all cases for a string literal type | |
| * type UserTypes = "admin" | "user" | "anonymous"; | |
| * | |
| * test.each(["admin", "user", "anonymous"] satisfies UnionToArray<UserTypes>) | |
| */ | |
| type UnionToArray< | |
| UnionType extends string, | |
| ArrayType extends string[] = [] | |
| > = { | |
| [StringLiteral in UnionType]: Exclude<UnionType, StringLiteral> extends never | |
| ? [...ArrayType, StringLiteral] | |
| : UnionToArray<Exclude<UnionType, StringLiteral>, [...ArrayType, StringLiteral]>; | |
| }[UnionType] & string[]; | |
| // Tests | |
| type SomeType = 'ONE' | 'TWO' | 'THREE' | 'FOUR' | 'FIVE' | 'SIX' | 'SEVEN' | 'EIGHT'; | |
| const ListOfSomeTypesOrdered: UnionToArray<SomeType> = ['ONE', 'TWO', 'THREE', 'FOUR', 'FIVE', 'SIX', 'SEVEN', 'EIGHT']; | |
| const ListOfSomeTypesUnorder: UnionToArray<SomeType> = ['ONE', 'TWO', 'FIVE', 'THREE', 'FOUR' ,'EIGHT', 'SIX', 'SEVEN']; | |
| // @ts-expect-error | |
| const ListOfSomeTypesMissing: UnionToArray<SomeType> = ['TWO', 'ONE', 'FIVE', 'FOUR']; | |
| // @ts-expect-error | |
| const ListOfSomeTypesUnknownValue: UnionToArray<SomeType> = ['ONE', 'TWO', 'THREE', 'FOUR', 'FIVE', 'SIX', 'ELEVEN']; | |
| // @ts-expect-error | |
| const ListOfSomeTypesLengthNotMatching: UnionToArray<SomeType> = ['ONE', 'TWO', 'THREE', 'FOUR', 'FIVE', 'SIX', 'SEVEN', 'EIGHT', 'EIGHT']; |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment