Run results for: js for in vs object.keys

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 11_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.4992.108 Safari/537.36

Browser: Chrome 102

Operating system: Mac OS X 11.1

Device Platform: Desktop

Date tested: 2 years ago

for in

2/s

object.keys

1/s

View exact numbers

Test name	Executions per second
✓ for in	2 Ops/sec
object.keys	1 Ops/sec

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for in
for (var i=10000; i > 0; i--) { for (var key in obj) { if (obj.hasOwnProperty(key)) { console.log(key); } } }
object.keys
for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => console.log(key)); }