I'm pleased to learn there are New JavaScript Set methods, as described by Brian Smith on MDN. Node is supporting it with version 22.0.0 (which is too modern for what I´m doing in a current project with Serverless Azure Functions). The Browsers are also supporting it (but Firefox only since version 127, which was released Jun 11, 2024. I think that is as well too modern to use it right now).
intersection()- returns a new set with elements in both this set and the given set.
union()- returns a new set with all elements in this set and the given set.
difference()- returns a new set with elements in this set but not in the given set.
symmetricDifference()- returns a new set with elements in either set, but not in both.
isSubsetOf()- returns a boolean indicating if all elements of a set are in a specific set.
isSupersetOf()- returns a boolean indicating if all elements of a set are in a specific set.
isDisjointFrom()- returns a boolean indicating if this set has no elements in common with a specific set.