Run results for: getOwnPropertyNames vs loop vs cached property names

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36 OPR/71.0.3770.198

Browser: Opera 71

Operating system: Mac OS X 10.15.6

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
getOwnPropertyNames	3646083.0 Ops/sec
Cached property names	2893950.0 Ops/sec
for in	9672401.0 Ops/sec
Object.keys	3655898.0 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