Run results for: for-in vs object.keys loop test

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.6 Safari/605.1.15

Browser: Safari 16

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Object.keys

111/s

for-in

97/s

View exact numbers

Test name	Executions per second
✓ Object.keys	111 Ops/sec
for-in	97 Ops/sec

Script Preparation code:

var obj = {};

for (var i=1000; i > 0; i--) {
  obj[""+i] = i;
}

Tests:

Object.keys
var ctr = 0; for (var i=100; i > 0; i--) { Object.keys(obj).forEach(key => ctr++); } console.log(ctr);
for-in
var ctr = 0; for (var i=100; i > 0; i--) { for(var key in obj) { ctr++; } } console.log(ctr);