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 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser: Chrome 121

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
✓ firstElementChild nextElementChild	12,925,617 Ops/sec
lastElementChild previousElementChild	11,244,260 Ops/sec
firstChild nextSibling	8,946,045 Ops/sec
children-- (into variable)	6,310,714 Ops/sec
ChildNodes for-- (direct)	4,185,252 Ops/sec
ChildNodes for (into variable)	3,845,286 Ops/sec
children-- (direct)	2,984,692 Ops/sec
children (direct)	1,797,328 Ops/sec
ChildNodes for-- (into variable)	1,620,655 Ops/sec
childNodes foreach	1,341,341 Ops/sec

Test name

Executions per second

✓ firstElementChild nextElementChild

12,925,617 Ops/sec

lastElementChild previousElementChild

11,244,260 Ops/sec

firstChild nextSibling

8,946,045 Ops/sec

children-- (into variable)

6,310,714 Ops/sec

ChildNodes for-- (direct)

4,185,252 Ops/sec

ChildNodes for (into variable)

3,845,286 Ops/sec

children-- (direct)

2,984,692 Ops/sec

children (direct)

1,797,328 Ops/sec

ChildNodes for-- (into variable)

1,620,655 Ops/sec

childNodes foreach

1,341,341 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]; }