EcmaScript | ES6 set.js

// Set - collection with unique values
const set = new Set()
const john = 'John'
const diana = 'Diana'
const kate = 'Kate'

set.add(john)
set.add(diana)
set.add(kate)

console.log(set.size) // Expected output: 3

set.add(john)
set.add(diana)
set.add(kate)

// Set can have only unique values and do nothing with duplicates
console.log(set.size) // Expected output: 3

// It could be useful to clear array from duplicates
const arr = [1,2,3,4,1,2,3,4,5,6,7,8]
const noDuplicates = Array.from(new Set(arr))
console.log(noDuplicates) // Expected output: [1, 2, 3, 4, 5, 6, 7, 8]