Type Alias OptionalKeysOf<Type>

OptionalKeysOf: Type extends unknown
    ? keyof {
        [Key in keyof Type as IsOptionalKeyOf<Type, Key> extends false
            ? never
            : Key]: never
    } & keyof Type
    : never

Extract all optional keys from the given type.

Copied from the OptionalKeysOf type in the type-fest package so that this package's public types do not depend on type-fest (see the note in type-checks.ts).