Run results for: Object loops: for...in vs Object.keys+forEach (ES5) vs for...of (ES6) vs Object.entries (ES8)

Run details:

User agent: Mozilla/5.0 (Linux; Android 14; SM-S928B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.6261.149 Mobile Safari/537.36 OPR/81.6.4292.79147

Browser: Opera Mobile 81

Operating system: Android

Device Platform: Mobile

Date tested: 2 years ago

Object.keys+forEach (ES5)

8K/s

for...of - keys (ES6)

8K/s

for...of - values (ES6)

7K/s

for...of - entries (ES8)

6K/s

Object.entries (ES8)

6K/s

for...in

5K/s

View exact numbers

Test name	Executions per second
✓ Object.keys+forEach (ES5)	8,041 Ops/sec
for...of - keys (ES6)	7,939 Ops/sec
for...of - values (ES6)	7,061 Ops/sec
for...of - entries (ES8)	5,888 Ops/sec
Object.entries (ES8)	5,881 Ops/sec
for...in	5,461 Ops/sec

Script Preparation code:

var obj = {};
for (let i = 0; i < 1000; i++) {
  obj['abc_' + i] = i;
}

function foo(bar) {
  return bar * 2 * 2;
}

Tests:

for...in
for (const key in obj) { if (obj.hasOwnProperty(key)) foo(obj[key]); }
Object.keys+forEach (ES5)
Object.keys(obj).forEach(function(key) { foo(obj[key]); });
for...of - keys (ES6)
for (const key of Object.keys(obj)) { foo(obj[key]); }
for...of - values (ES6)
for (const value of Object.values(obj)) { foo(value); }
for...of - entries (ES8)
for (const [key, value] of Object.entries(obj)) { foo(value); }
Object.entries (ES8)
Object.entries(obj).forEach(function(key, value) { foo(value); });