Run results for: set + array.from + map vs map + set

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36

Browser: Chrome 103

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
map + set	14128.9 Ops/sec
set + array.from + map	4993.2 Ops/sec

Script Preparation code:

var array = []

for (let i = 0; i < 10000; i++) {
  array.push(Math.round(Math.random() * 100))
}

​x
 
var array = []​for (let i = 0; i < 10000; i++) {  array.push(Math.round(Math.random() * 100))}​

Tests:

const set = new Set()

array.map((item) => {
  if (set.has(item)) {
    set.add(item)
    return item
  }
})

 
const set = new Set()​array.map((item) => {  if (set.has(item)) {    set.add(item)    return item  }})