Benchmark: JavaScript Array Performance — for vs for...of vs for...in vs forEach vs reduce

JavaScript Array Performance — for vs for...of vs for...in vs forEach vs reduce (version: 1)

Compare the performance of five ways to traverse an array and accumulate a computed numeric result. All test cases execute the same work on the same input data. Note that for...in enumerates property keys rather than using the array iterator, so its semantics differ from for, for...of, forEach, and reduce.

Comparing performance of: `for vs for...of vs for...in vs forEach vs reduce`

Created: 4 months ago by: Guest

Go to the latest result

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const arraySize = 100_000;
const values = Array.from({ length: arraySize }, (_, index) => index);

function computeValue(value) {
  return (value * 3 + 7) % 97;
}

let blackhole = 0;

Tests:

for
let sum = 0; for (let index = 0; index < values.length; index += 1) { sum += computeValue(values[index]); } blackhole = sum; return blackhole;
for...of
let sum = 0; for (const value of values) { sum += computeValue(value); } blackhole = sum; return blackhole;
for...in
let sum = 0; for (const index in values) { sum += computeValue(values[index]); } blackhole = sum; return blackhole;
forEach
let sum = 0; values.forEach((value) => { sum += computeValue(value); }); blackhole = sum; return blackhole;
reduce
const sum = values.reduce((accumulator, value) => { return accumulator + computeValue(value); }, 0); blackhole = sum; return blackhole;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
for...of
for...in
forEach
reduce

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/148.0.0.0 Safari/537.36 Edg/148.0.0.0

Browser/OS: Chrome 148 on Windows

View result in a separate tab

for...of

3K/s

for

2K/s

forEach

1K/s

reduce

770/s

for...in

166/s

View exact numbers

Test name	Executions per second
✓ for...of	2,618 Ops/sec
for	1,726 Ops/sec
forEach	1,120 Ops/sec
reduce	770 Ops/sec
for...in	166 Ops/sec