NonNullable<T>
Constructs a type by excluding null and undefined from T.
Syntax
NonNullable<Type>Returns
type — T with the null and undefined members removed.
Examples
type T = string | null | undefined;
type Clean = NonNullable<T>; // string
function first<T>(arr: T[]): NonNullable<T> {
return arr[0] as NonNullable<T>;
}
Notes
Since TS 4.8 it is implemented as `T & {}`, which strips `null` and
`undefined` while preserving the rest of the type. Useful after filtering
nullish values or when narrowing optional results.