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

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36

Browser: Chrome 73

Operating system: Linux

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
_.isEmpty	45370.7 Ops/sec
Object.keys().length	304787.1 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;