Set is different than Map

[marwahaha]

I noticed this section of the book

Set and WeakSet
Set and WeakSet are identical to Map, except for 2 major differences:

Instead of .set for values, you use .add() to create a key value pair to store.
All values in a Set must be unique and only occur once.
As far as everything else, they are very identical and are ordered.

If you need a Map-like storage or cache, but all values must be unique, then Set is perfect!

Just like WeakMap, WeakSet allows unused references to be garbage collected, and it cannot be iterated upon.

I think Set is not exactly a key-value store, but just a "value" store.

[MrBenJ]

Awesome. This is a really great catch. I'm going to write up something for this section and make a PR for this later sometime.

Thanks for catching this!