import type { OptionalKeysOf } from "./optional-keys-of.mjs";
/**
Extract all required keys from the given type.

This is useful when you want to create a new type that contains different type values for the required keys only or use the list of keys for validation purposes, etc...

@example
```
import type {RequiredKeysOf} from 'type-fest';

declare function createValidation<Entity extends object, Key extends RequiredKeysOf<Entity> = RequiredKeysOf<Entity>>(field: Key, validator: (value: Entity[Key]) => boolean): ValidatorFn;

interface User {
name: string;
surname: string;

luckyNumber?: number;
}

const validator1 = createValidation<User>('name', value => value.length < 25);
const validator2 = createValidation<User>('surname', value => value.length < 25);
```

@group type-fest
*/
export type RequiredKeysOf<BaseType extends object> = BaseType extends unknown ? Exclude<keyof BaseType, OptionalKeysOf<BaseType>> : never;