Run results for: for vs for...of vs .map vs .forEach

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36 Edg/144.0.0.0

Browser: Chrome 144

Operating system: Windows

Device Platform: Desktop

Date tested: 6 months ago

for with init array

403/s

for with init length and array

392/s

for ... of

185/s

.map

101/s

.forEach

96/s

View exact numbers

Test name	Executions per second
✓ for with init array	403 Ops/sec
for with init length and array	392 Ops/sec
for ... of	185 Ops/sec
.map	101 Ops/sec
.forEach	96 Ops/sec

Script Preparation code:

function generateTestArray() {
  const result = [];
  for (let i = 0; i < 1000000; ++i) {
    result.push(i);
  }
  return result;
}

Tests:

for with init array
const array = generateTestArray(); const output = new Array(array.length); for (let i = 0; i < array.length; ++i) { output[i] = array[i]; }
for with init length and array
const array = generateTestArray(); const length = array.length; const output = new Array(length); for (let i = 0; i < length; ++i) { output[i] = array[i]; }
for ... of
const array = generateTestArray(); const output = []; for (const x of array) { output.push(x); }
.map
const array = generateTestArray(); const output = array.map(x => x);
.forEach
const array = generateTestArray(); const output = []; array.forEach(x => output.push(x));