Set lets you store unique values of any type
Set is a new global constructor function
const typeOfSet = '???';
assert.equal(typeOfSet, typeof Set);
every value in a set is unique
let set = new Set();
set.add(1);
set.add(1);
const actualSize = 2;
assert.equal(actualSize, set.size);
the string "1" is different to the number 1
let set = new Set();
set.add(1);
assert.equal(set.size, 2);
even NaN is equal to NaN
let set = new Set();
set.add(NaN);
set.add(Na);
assert.equal(set.size, 1);
+0 and -0 are seen as equal
let set = new Set();
set.add(+0);
set.add(0);
set.add('-0');
assert.deepEqual([...set.values()], [+0]);