Benchmark: Performance of JavaScript .forEach() vs for()

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;
}

Tests:

.forEach
const array = generateTestArray(); array.forEach((x) => { x.r = x.a + x.b; });
.for (init array)
const array = generateTestArray(); const r = new Array(array.length); for (let i = 0; i < array.length; ++i) { r[i] = array[i].a + array[i].b; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.forEach
.for (init array)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:128.0) Gecko/20100101 Firefox/128.0

Browser/OS: Firefox 128 on Windows

View result in a separate tab

Test name	Executions per second
.forEach	18.6 Ops/sec
.for (init array)	19.9 Ops/sec

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Performance of JavaScript .forEach() vs for() (version: 1)

Comparing performance of: .forEach vs .for (init array)

Created: 7 months ago by: Guest

Jump to the latest result

.forEach

.for (init array)

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A