| 1234567891011121314151617181920212223242526272829303132333435 |
- // TODO: Remove this when we target TypeScript >=3.5.
- type _Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>;
- /**
- Create a type that requires exactly one of the given keys and disallows more. The remaining keys are kept as is.
- Use-cases:
- - Creating interfaces for components that only need one of the keys to display properly.
- - Declaring generic keys in a single place for a single use-case that gets narrowed down via `RequireExactlyOne`.
- The caveat with `RequireExactlyOne` is that TypeScript doesn't always know at compile time every key that will exist at runtime. Therefore `RequireExactlyOne` can't do anything to prevent extra keys it doesn't know about.
- @example
- ```
- import {RequireExactlyOne} from 'type-fest';
- type Responder = {
- text: () => string;
- json: () => string;
- secure: boolean;
- };
- const responder: RequireExactlyOne<Responder, 'text' | 'json'> = {
- // Adding a `text` key here would cause a compile error.
- json: () => '{"message": "ok"}',
- secure: true
- };
- ```
- */
- export type RequireExactlyOne<ObjectType, KeysType extends keyof ObjectType = keyof ObjectType> =
- {[Key in KeysType]: (
- Required<Pick<ObjectType, Key>> &
- Partial<Record<Exclude<KeysType, Key>, never>>
- )}[KeysType] & _Omit<ObjectType, KeysType>;
|
