Run results for: Array.includes() vs Set.has()

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_1_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.1.1 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 18

Operating system: iOS 18.1.1

Device Platform: Mobile

Date tested: one year ago

Set.has, 10 000 elements

33.3M/s

Set.has, 1 000 000 elements

30.9M/s

Array.includes, 10 000 elements

56K/s

Array to Set + Set.has, 10 000 elements

6K/s

Array to Set + Set.has x 100, 10 000 elements

6K/s

Array.includes x 100, 10 000 elements

562/s

Array.includes, 1 000 000 elements

551/s

View exact numbers

Test name	Executions per second
✓ Set.has, 10 000 elements	33,326,614 Ops/sec
Set.has, 1 000 000 elements	30,924,446 Ops/sec
Array.includes, 10 000 elements	56,331 Ops/sec
Array to Set + Set.has, 10 000 elements	6,474 Ops/sec
Array to Set + Set.has x 100, 10 000 elements	6,371 Ops/sec
Array.includes x 100, 10 000 elements	562 Ops/sec
Array.includes, 1 000 000 elements	551 Ops/sec

Script Preparation code:

function getArray(length) {
  const result = [];
  for (let i = 0; i < length; i++) {
    result.push(i + 'abc'); // In case the browser does some sort of optimization for arrays with only integers ¯\_(ツ)_/¯
  }
  return result;
}

function getRandomTargetElement(arrayLength) {
  const index = Math.floor(Math.random() * arrayLength);
  return index + 'abc';
}


array_small = getArray(10000);
array_large = getArray(1000000);

set_small = new Set(array_small);
set_large = new Set(array_large);

Tests:

Array.includes, 10 000 elements
array_small.includes(getRandomTargetElement(10000));
Array.includes, 1 000 000 elements
array_large.includes(getRandomTargetElement(1000000))
Set.has, 10 000 elements
set_small.has(getRandomTargetElement(10000))
Set.has, 1 000 000 elements
set_large.has(getRandomTargetElement(1000000))
Array to Set + Set.has, 10 000 elements
const target = getRandomTargetElement(10000); const set = new Set(array_small); set.has(target)
Array to Set + Set.has x 100, 10 000 elements
const set = new Set(array_small); for (let i = 0; i < 100; i++) { const target = getRandomTargetElement(10000); set.has(target) }
Array.includes x 100, 10 000 elements
for (let i = 0; i < 100; i++) { const target = getRandomTargetElement(10000); array_small.includes(target) }