Run results for: Object.keys + for vs Object.values + for vs for...in

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:121.0) Gecko/20100101 Firefox/121.0

Browser: Firefox 121

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

for...in

181/s

Object.values + for

178/s

Object.keys + for

175/s

View exact numbers

Test name	Executions per second
✓ for...in	181 Ops/sec
Object.values + for	178 Ops/sec
Object.keys + for	175 Ops/sec

Script Preparation code:

function randNum(max, min) {
	const x = Math.floor(Math.random() * max)
	if (!isFinite(min) && x < min) {
		return min
	}
	return x
}

function randString(max, min, base) {
	let len = randNum(max)
	if (min && len < min) {len = min}
	if (len > max) {len = max}

	let arr = new Uint8Array(len / 2)
	window.crypto.getRandomValues(arr)
	return Array.from(arr, (dec)=> (
		dec.toString(base || 36).padStart(2, '0')
	)).join('')
}

var obj = {};
for(let i = 0; i < 1000; i++) {
  const id = randString(32,32);
  obj[id] = {
    id,
    firstName: randString(40,5),
    lastName: randString(40,5),
    email: randString(40,5),
    address: {
      country: randString(40,5),
      state: randString(40,5),
    },
  };
}

Tests:

Object.keys + for
const keys = Object.keys(obj); for (let i = 0; i < keys.length; i++) {const el = obj[keys[i]]; console.count('keys + for')}
Object.values + for
const values = Object.values(obj); for (let i = 0; i < values.length; i++) {const el = values[i]; console.count('values + for')}
for...in
for (const key in obj) {const el = obj[key]; console.count('for...in')}