ts-toolbelt
Version:
TypeScript's largest utility library
17 lines (16 loc) • 426 B
TypeScript
/**
* @hidden
*/
export declare type _UndefinableKeys<O extends object> = {
[K in keyof O]-?: [O[K] & (undefined)] extends [never] ? never : K;
}[keyof O];
/**
* Get the keys of `O` that are `undefined`
* (⚠️ needs `--strictNullChecks` enabled)
* @param O
* @returns [[Key]]
* @example
* ```ts
* ```
*/
export declare type UndefinableKeys<O extends object> = O extends unknown ? _UndefinableKeys<O> : never;