Run results for: checks if object has any key - Object.keys vs for key in 2

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:139.0) Gecko/20100101 Firefox/139.0

Browser: Firefox 139

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Object.keys	78585144.0 Ops/sec
for key .. in	39456268.0 Ops/sec

Script Preparation code:

var obj = {}
new Array(1000).map((item, index) => {
    obj[index] = index
})

Tests: