Run results for: For in vs Object.keys.forEach

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Firefox/91.0

Browser: Firefox 91

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
For In	773.0 Ops/sec
Object keys forEach	765.5 Ops/sec

Script Preparation code:

var obj = new Object()
var keys = (new Array(100)).fill(0).map((x, i) => { return i + 1 })
keys.forEach((x) => { obj['prop' + x] = x })

Tests:

For In
for (var key in obj) { if (obj.hasOwnProperty(key)) console.log(obj[key]) }
Object keys forEach
Object.keys(obj).forEach(key => console.log(obj[key]))