set.js

'use strict'
let groceryList = new Set()
groceryList
  .add('Bananas')
  .add('Apples')
  .add('Grapes')
  .add('Kiwis')
  .add('Pears')
  .add('Apples') // dublicates will be ignored

console.log(groceryList.size === 5)
console.log(groceryList.has('Kiwis') === true)

for (let item of groceryList) {
  console.log(item)
}

console.log(groceryList.size === 5)
groceryList.delete('Kiwis')
console.log(groceryList.size === 4)

groceryList.clear()
console.log(groceryList.size === 0)