Run results for: for..of against Map.entries vs for..in 2

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.1.2 Safari/605.1.15

Browser: Safari 17

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Map.foreach

5K/s

for..of Map.entries()

4K/s

for..of Map.entries() no destructuring

4K/s

View exact numbers

Test name	Executions per second
✓ Map.foreach	4,747 Ops/sec
for..of Map.entries()	4,033 Ops/sec
for..of Map.entries() no destructuring	3,938 Ops/sec

Script Preparation code:

var array = Array.from({ length: 10000 }, () => {
  const n = Math.floor(Math.random() * 100)
  if (n > 26) {
    return n
  } else {
    return String.fromCharCode('a'.charCodeAt(0) + n);
  }
});
var obj = new Map();
for (let i = 0; i < array.length; i++) {
  obj.set(i, array[i]);
}

Tests:

for..of Map.entries()
for (const [key, val] of obj.entries()) { const foo = val + 'a'; }
Map.foreach
obj.forEach((val) => { const foo = val + 'a'; })
for..of Map.entries() no destructuring
for (const entry of obj.entries()) { const key = entry[0]; const val = entry[1]; const foo = val + 'a'; }