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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser: Chrome 121

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Set.has, 10 000 elements

1.9M/s

Set.has, 1 000 000 elements

1.0M/s

Array.includes, 10 000 elements

37K/s

Array to Set + Set.has, 10 000 elements

2K/s

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

1K/s

Array.includes x 100, 10 000 elements

372/s

Array.includes, 1 000 000 elements

313/s

View exact numbers

Test name	Executions per second
✓ Set.has, 10 000 elements	1,931,844 Ops/sec
Set.has, 1 000 000 elements	1,001,561 Ops/sec
Array.includes, 10 000 elements	37,268 Ops/sec
Array to Set + Set.has, 10 000 elements	1,612 Ops/sec
Array to Set + Set.has x 100, 10 000 elements	1,450 Ops/sec
Array.includes x 100, 10 000 elements	372 Ops/sec
Array.includes, 1 000 000 elements	313 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) }