Big O and sets in Javascript

Question

What are the Big-O notations for Sets in Javascript? Is it always faster than an array? Additionally, can you tell me where I should be looking here for sets? (i.e. what category does it fall under... is it hash table?)

Answer 1

add, delete and has is at least O(log n) or even O(1)

forEach, entries, values, keys traversal is O(n)

Is it always faster than an array?

No, traversal is roughly at the same speed.