Run results for: for-in vs object.keys

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:59.0) Gecko/20100101 Firefox/59.0

Browser: Firefox 59

Operating system: Mac OS X 10.13

Device Platform: Other

Date tested: 6 years ago

Test name	Executions per second
for-in	0.6 Ops/sec
Object.keys	0.5 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) { console.log(key); } }
Object.keys
for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => console.log(key)); }