In this blog post, we examine the ECMAScript proposal “Set methods for JavaScript” by Michał Wadas, Sathya Gunasekara and Kevin Gibbons. It introduces new methods for Sets. New Set methods that return Sets # Set.prototype.union(other) # This method returns a Set that is the union of this and other. Type signature: Set<T>.prototype.union(other: SetReadOperations<T>): Set<T> The type of other, Set