Run results for: reduce + spread vs map + flat

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36 OPR/119.0.0.0

Browser: Opera 119

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

reduce + spread

42K/s

map + flat

19K/s

View exact numbers

Test name	Executions per second
✓ reduce + spread	42,497 Ops/sec
map + flat	19,212 Ops/sec

Script Preparation code:

function generateTestArray() {
  const result = [];
  for (let i = 0; i < 1000; ++i) {
    result.push({
      a: [i, i * 2, i * 3]
    });
  }
  return result;
}

Tests:

reduce + spread
const arr = generateTestArray(); const result = arr.reduce((acc, el) => { acc.push(...el.a); return acc; }, []);
map + flat
const arr = generateTestArray(); const result = arr.map(el => el.a).flat();