Run results for: Unique elements of two arrays

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.106 YaBrowser/21.6.0.1108 Yowser/2.5 Safari/537.36

Browser: Yandex Browser 21

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Set + spread	351.9 Ops/sec
Set + Array.from	356.4 Ops/sec
Concat + spread	315.0 Ops/sec
lastIndexOf	82.9 Ops/sec

Script Preparation code:

var array1 = [];
for (let i = 0; i < 100000; i++) {
   array1.push(Math.floor((Math.random() * 10) + 1));
}
var array2 = [];
for (let i = 0; i < 100000; i++) {
   array2.push(Math.floor((Math.random() * 10) + 1));
}

Tests:

Set + spread
const uniqueValues = (arr1, arr2) => { const values = new Set(arr1) for(const value of arr2) { values.add(value) } return [...values] } uniqueValues(array1, array2)
Set + Array.from
const uniqueValues = (arr1, arr2) => { const values = new Set(arr1) for(const value of arr2) { values.add(value) } return Array.from(values) } uniqueValues(array1, array2)
Concat + spread
const uniqueValues = (arr1, arr2) => { return [...new Set(arr1.concat(arr2))] for(const value of arr2) { values.add(value) } return [...values] } uniqueValues(array1, array2)
lastIndexOf
const uniqueValues = (arr1, arr2) => { const array = arr1.concat(arr2) return array.filter((item, index) => array.lastIndexOf(item) != index); } uniqueValues(array1, array2)

Run results for: Unique elements of two arrays

Set + spread

Set + Array.from

Concat + spread

lastIndexOf