Run results for: Fastest way to list children: childNodes vs children vs firstChild/nextSibling vs firstElementChild/nextElementSibling v2

Result: firstElementChild is the fastest yielding 3-4X performance. With lastElementChild close 2nd. Other observations: doing for loop i-- with children shows ~150% higher performance vs i++. And unloading it into a variable prior yields another ~200% boost

Go to the benchmark

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser: Chrome 122

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
✓ lastElementChild previousElementChild	12,141,695 Ops/sec
firstElementChild nextElementChild	12,091,137 Ops/sec
firstChild nextSibling	7,930,568 Ops/sec
children-- (into variable)	7,771,758 Ops/sec
ChildNodes for-- (direct)	5,035,169 Ops/sec
ChildNodes for (into variable)	3,730,450 Ops/sec
children-- (direct)	3,470,958 Ops/sec
children (direct)	2,027,795 Ops/sec
ChildNodes for-- (into variable)	1,845,005 Ops/sec
childNodes foreach	1,652,042 Ops/sec

Test name

Executions per second

✓ lastElementChild previousElementChild

12,141,695 Ops/sec

firstElementChild nextElementChild

12,091,137 Ops/sec

firstChild nextSibling

7,930,568 Ops/sec

children-- (into variable)

7,771,758 Ops/sec

ChildNodes for-- (direct)

5,035,169 Ops/sec

ChildNodes for (into variable)

3,730,450 Ops/sec

children-- (direct)

3,470,958 Ops/sec

children (direct)

2,027,795 Ops/sec

ChildNodes for-- (into variable)

1,845,005 Ops/sec

childNodes foreach

1,652,042 Ops/sec

Tests:

childNodes foreach
parent.childNodes.forEach(function (node) { let n = node; });
children (direct)
for (let i = 0; i < parent.children.length; i++) { let n = parent.children[i]; }
firstChild nextSibling
let elem = parent.firstChild; do { let n = elem; } while (elem = elem.nextSibling)
firstElementChild nextElementChild
let elem = parent.firstElementChild; do { let n = elem; } while (elem = elem.nextElementSibling)
ChildNodes for (into variable)
let children = parent.childNodes; for (let i = 0; i < children.length; i++) { let n = children[i]; }
children-- (direct)
for (let i = parent.children.length-1; i >= 0; i--) { let n = parent.children[i]; }
ChildNodes for-- (into variable)
for (let i = parent.childNodes.length-1; i >= 0; i--) { let n = parent.childNodes[i]; }
ChildNodes for-- (direct)
let children = parent.childNodes; for (let i = children.length-1; i >= 0; i--) { let n = children[i]; }
lastElementChild previousElementChild
let elem = parent.lastElementChild; do { let n = elem; } while (elem = elem.previousElementSibling)
children-- (into variable)
let children = parent.children for (let i = children.length-1; i >= 0; i--) { let n = children[i]; }