Run results for: Iterating over objects and maps

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.6 Safari/605.1.15

Browser: Safari 16

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
for..of destructured with Object.entries()	354.6 Ops/sec
for..of undestructured with Object.entries()	434.6 Ops/sec
for..in	509.2 Ops/sec
for..of destructured with Object.entries() (with prototype)	222.0 Ops/sec
for..of undestructured with Object.entries() (with prototype)	217.6 Ops/sec
for..in (with prototype)	230.9 Ops/sec
for..of destructured with map	853.4 Ops/sec
for..of undestructured with map	1213.6 Ops/sec
.forEach with Object.entries()	158.1 Ops/sec
.forEach with Object.entries() (with prototype)	344.6 Ops/sec
.forEach with map	4509.2 Ops/sec

Script Preparation code:

var obj = Object.create(null);
var obj2 = {};
var map = new Map();
for (let i = 0;i < 10000; i++) {
  let j
  const n = Math.floor(Math.random() * 100)
  if (n > 26) {
    j = n
  } else {
    j = String.fromCharCode('a'.charCodeAt(0) + n);
  }
  obj[i] = j;
  obj2[i] = j;
  map.set(i, j);
}

Tests:

for..of destructured with Object.entries()
for (const [key, val] of Object.entries(obj)) { const keyval = key + val; }
for..of undestructured with Object.entries()
for (const entry of Object.entries(obj)) { const key = entry[0]; const val = entry[1]; const keyval = key + val; }
for..in
for (const key in obj) { const val = obj[key]; const keyval = key + val; }
for..of destructured with Object.entries() (with prototype)
for (const [key, val] of Object.entries(obj2)) { const keyval = key + val; }
for..of undestructured with Object.entries() (with prototype)
for (const entry of Object.entries(obj2)) { const key = entry[0]; const val = entry[1]; const keyval = key + val; }
for..in (with prototype)
for (const key in obj2) { const val = obj[key]; const keyval = key + val; }
for..of destructured with map
for (const [key, val] of map) { const keyval = key + val; }
for..of undestructured with map
for (const entry of map) { const key = entry[0]; const val = entry[1]; const keyval = key + val; }
.forEach with Object.entries()
Object.entries(obj).forEach(([key, val]) => { const keyval = key + val; });
.forEach with Object.entries() (with prototype)
Object.entries(obj2).forEach(([key, val]) => { const keyval = key + val; });
.forEach with map
map.forEach((key, val) => { const keyval = key + val; });

Run results for: Iterating over objects and maps

for..of destructured with Object.entries()

for..of undestructured with Object.entries()

for..in

for..of destructured with Object.entries() (with prototype)

for..of undestructured with Object.entries() (with prototype)

for..in (with prototype)

for..of destructured with map

for..of undestructured with map

.forEach with Object.entries()

.forEach with Object.entries() (with prototype)

.forEach with map