Run results for: Object.keys.length vs sum with for

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.108 Safari/537.36

Browser: Chrome 74

Operating system: Mac OS X 10.14.4

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
_.isEmpty	60456.4 Ops/sec
Object.keys().length	351635.9 Ops/sec

Script Preparation code:

window.obj = {};

for (var i = 0, len = 100; i < len; i++) {
  obj['key' + i] = 'value' + i;
}

Tests:

_.isEmpty
let len = 0; for (const key in obj) { if (obj.hasOwnProperty(key)) { len++; } }
Object.keys().length
let len = Object.keys(window.obj).length;