When defining a union or intersection in TypeScript, it is possible to mistakenly include type constituents that encompass other constituents, that
don’t have any effect, or that are more restrictive. For instance,
- The type
something in any | something is redundant because any covers all possible types, whatever
something is.
- The types
never in unions like never | something or unknown in intersections like unknown &
something are effectless.
- More restrictive types in intersections like the literal type
1 in 1 & number reduce the set of possible values
to specific ones.
Eliminating redundant types from a union or intersection type simplifies the code and enhances its readability. Moreover, it provides a clearer
representation of the actual values that a variable can hold.
