Hashmaps and Time Complexity

• My understanding is ES6 Map object can implement a Hashmap in Javascript. Is that correct?
• indexOf method in arrays has an O(n) time complexity.
• Does has method in Maps have O(1) time complexity? If yes why? How JS can find an element in a Map object in one step? How it works differently than indexOf? If not having an O(1) then Es6 Map is not a real Hashmap...

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