Sets in JS (and spread operator)

Constructor

s= new Set()

Set {}

Methods

s.add(45)

s.add(34)

Set {45, 34}

s.clear()

Set {}

Using the spread operator to convert a set to an array

let t = new Set([...s].filter(x=>x ==34))

t

Set {34}

using spread to concatenate sets

x = [s,t]

[Set, Set]//unspread

x=[...s,...t]

[45, 34, 34]//spread

Intersect

new Set([...s].filter(x=>t.has(x)))

Set {34}

difference

new Set([...s].filter(x=>!t.has(x)))

Set {45}