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When should you use Map and Set over objects and arrays?

Q: When should you use Map and Set over objects and arrays?

**Core concept (TL;DR).** Use a Map instead of a plain object when you need a true **dictionary**: keys of **any type**, reliable **insertion order**, a .size , and frequent add/delete. Use a Set instead of an array when you need a collection of **unique values** with fast membership tests. Map = keyed dictionary · Set = unique values Map vs Object <text x="13

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