Benchmark: Performance of JavaScript .forEach vs for in

Script Preparation code:

function generateTestObject() {
  const result = {};
  for (let i = 0; i < 10000; ++i) {
    result['v'+i] = i
  }
  return result;
}

Tests:

Object.entries()
const object = generateTestObject(); Object.entries(object).forEach(([key, value]) => { const test = key + '' + value })
for in
const object = generateTestObject(); for(key in object){ const test = key + '' + object[key] }
for in with variable
const object = generateTestObject(); for(key in object){ const value = object[key] const test = key + '' + value }

Rendered benchmark preparation results:

Previous results

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Mac OS X 10.15.7

Object.entries()

399/s

for in

384/s

for in with variable

383/s

View exact numbers

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