Run results for: for-in vs object.keys (many keys)

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:141.0) Gecko/20100101 Firefox/141.0

Browser: Firefox 141

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

for-in

24/s

Object.keys

24/s

View exact numbers

Test name	Executions per second
✓ for-in	24 Ops/sec
Object.keys	24 Ops/sec

Script Preparation code:

var obj = Object.fromEntries(Array.from({
    length: 1000
}, (_, i) => [i.toString(), i]));

Tests:

for-in
for (let i=10; i > 0; i--) { for (let key in obj) console.log(key); }
Object.keys
for (let i=10; i > 0; i--) { for(let key of Object.keys(obj)) console.log(key); }