Run results for: Performance of JavaScript .forEach, for in v3

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0

Browser: Firefox 128

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

.forEach

6/s

for..of destructured

6/s

for..of

6/s

.forEach destructured

6/s

View exact numbers

Test name	Executions per second
✓ .forEach	6 Ops/sec
for..of destructured	6 Ops/sec
for..of	6 Ops/sec
.forEach destructured	6 Ops/sec

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 destructured
const array = generateTestArray(); const newMap = new Map(); array.forEach(({a, b}) => { newMap.set(a, b); }); const foo = [...newMap.entries()];
for..of destructured
const array = generateTestArray(); const newMap = new Map(); for(const {a, b} of array) { newMap.set(a, b); } const foo = [...newMap.entries()];
.forEach
const array = generateTestArray(); const newMap = new Map(); array.forEach((x) => { const {a, b} = x; newMap.set(a, b); }); const foo = [...newMap.entries()];
for..of
const array = generateTestArray(); const newMap = new Map(); for(const x of array) { const {a, b} = x; newMap.set(a, b); } const foo = [...newMap.entries()];