Run results for: js array perfomance

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.164 Safari/537.36

Browser: Chrome 91

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Array.forEach	66.4 Ops/sec
for of	230.9 Ops/sec
for <array.length, indexing	4.4 Ops/sec
for <len, indexing	5.8 Ops/sec
for <array.length, tmp element	8.6 Ops/sec
for <len, tmp element	16.6 Ops/sec

Script Preparation code:

function generateTestArray() {
  const result = [];
  for (let i = 0; i < 1000000; ++i) {
    result.push({
      a: i,
      b: i / 2,
      r: 0,
    });
  }
  return result;
}

var array = generateTestArray();

Tests:

Array.forEach
array.forEach((x) => { x.r = x.a + x.b; });
for of
for (const obj of array) { obj.r = obj.a + obj.b; }
for <array.length, indexing
for (let i = 0; i < array.length; ++i) { array[i].r = array[i].a + array[i].b; }
for <len, indexing
const len = array.length; for (let i = 0; i < len; ++i) { array[i].r = array[i].a + array[i].b; }
for <array.length, tmp element
for (let i = 0; i < array.length; ++i) { const x = array[i]; x.r = x.a + x.b; }
for <len, tmp element
const len = array.length; for (let i = 0; i < len; ++i) { const x = array[i]; x.r = x.a + x.b; }

Run results for: js array perfomance

Array.forEach

for of

for <array.length, indexing

for <len, indexing

for <array.length, tmp element

for <len, tmp element