Run results for: for-in vs object.keys

Run details:

User agent: Mozilla/5.0 (Linux; Android 8.0.0; XT1635-02) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.105 Mobile Safari/537.36

Browser: Chrome Mobile 72

Operating system: Android 8.0.0

Device Platform: Mobile

Date tested: 5 years ago

Test name	Executions per second
for-in	5.0 Ops/sec
Object.keys	3.6 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=1000; i > 0; i--) { for (var key in obj) { console.log(key); } }
Object.keys
for (var i=1000; i > 0; i--) { Object.keys(obj).forEach(key => console.log(key)); }