Run results for: getOwnPropertyNames vs loop vs cached property names

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 14_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/93.0.4577.39 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 93

Operating system: iOS 14.2

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
getOwnPropertyNames	5819257.0 Ops/sec
Cached property names	4951505.0 Ops/sec
for in	9811998.0 Ops/sec
Object.keys	5857029.0 Ops/sec

Script Preparation code:

var obj = {
  $names : ['a','b','c'],
  a:1,
  b:2,
  c:3
}

Tests:

getOwnPropertyNames
var ks = Object.getOwnPropertyNames(obj); var n = 0; for (var i = 0; i < ks.length; i++) { var k = ks[i]; if (k.charAt(0) == '$') continue; n++; }
Cached property names
var ks = obj['$names']; var n = 0; for (var i = 0; i < ks.length; i++) { var k = obj[ks[i]]; n++; }
for in
var n = 0; for (var k in obj) { if (k.charAt(0) == '$') continue; n++; }
Object.keys
var ks = Object.keys(obj); var n = 0; for (var i = 0; i < ks.length; i++) { var k = ks[i]; if (k.charAt(0) == '$') continue; n++; }

Run results for: getOwnPropertyNames vs loop vs cached property names

getOwnPropertyNames

Cached property names

for in

Object.keys