isSubsetOfintermediateconst a = new Set([1, 2])
const b = new Set([1, 2, 3])
a.isSubsetOf(b) // β true
b.isSubsetOf(a) // β falseUse Set.isSubsetOf() to check whether every element of this set is also in another set.
A Set is a subset of itself (equal sets are subsets of each other).
Challenge: Verify that equal Sets are subsets of each other.