types-kit.lastinunion.md

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LastInUnion type

Get the last type in a union type (important!: the result is random when you are using tsc, the correct type can only be obtained through the editor environment).

Signature:

export type LastInUnion<U> = UnionToIntersection<
  U extends unknown ? (x: U) => 0 : never
> extends (x: infer L) => 0
  ? L
  : never

References: UnionToIntersection

Example

// Expect: 2
type Foo = LastInUnion<1 | 2>

if it is necessary to output one type from overload, TS selects the last signature in the overload.