deep-non-nullable

DeepNonNullable<Type> constructs a type by picking all properties from type Type recursively and exclude null and undefined property values from all of them

interface DeepNullableCompany {
  name: string | null | undefined;
  employees: ({ name: string | null | undefined } | null | undefined)[] | null | undefined;
}

type Company = DeepNonNullable<DeepNullableCompany>;
//   ^? { name: string; employees: { name: string }[] }

Useful when object type, where property values can be either undefined or null, is a source of truth and you need to have non-nullable object type, meaning property values cannot be either undefined or null

TS Playground – https://tsplay.dev/wE75ym

It's different from DeepRequired as it doesn't change optional field:

interface Person {
  name?: string | null | undefined;
}

type RequiredPerson = DeepRequired<Person>;
//   ^? { name: string | null; }
type NonNullablePerson = DeepNonNullable<Person>;
//   ^? { name?: string | undefined; }

TS Playground – https://tsplay.dev/N9jy8m