# UnionToIntersection

`type` in `utils` · v0.6.1

<https://docs.seedcord.org/packages/utils/0.6.1/types/union-to-intersection>

Convert a union type to an intersection type.

Inspired by [this Stack Overflow answer](https://stackoverflow.com/a/50375286/2172153).

## Examples

```ts
import type {UnionToIntersection} from 'type-fest';

type Union = {the(): void} | {great(arg: string): void} | {escape: boolean};

type Intersection = UnionToIntersection<Union>;
//=> {the(): void} & {great(arg: string): void} & {escape: boolean}

 Type
```

## Declaration

```ts
type UnionToIntersection<Union> = (// `extends unknown` is always going to be the case and is used to convert the // `Union` into a [distributive conditional // type](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-8.html#distributive-conditional-types). Union extends unknown // The union type is used as the only argument to a function since the union // of function arguments is an intersection. ? (distributedUnion: Union) => void // This won't happen. : never // Infer the `Intersection` type since TypeScript represents the positional // arguments of unions of functions as an intersection of the union. ) extends ((mergedIntersection: infer Intersection) => void) // The `& Union` is to ensure result of `UnionToIntersection<A | B>` is always assignable to `A | B` ? Intersection & Union : never
```