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 Fastest way to list children: childNodes vs children vs firstChild/nextSibling vs firstElementChild/nextElementSibling v2 (version: 0)

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

Comparing performance of: childNodes foreach vs children (direct) vs firstChild nextSibling vs firstElementChild nextElementChild vs ChildNodes for (into variable) vs children-- (direct) vs ChildNodes for-- (into variable) vs ChildNodes for-- (direct) vs lastElementChild previousElementChild vs children-- (into variable)

Created: 3 years ago by: Guest
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HTML Preparation code:
​x
 
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<html>
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​
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<body>
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    <div id='test'>
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        <div name='a'></div>
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        <div name='b'></div>
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        <div name='c'></div>
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    </div>
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</body>
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​
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</html>
Script Preparation code:
 
var parent = document.getElementById('test');
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];
    }
Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Experimental features:

  • Test case name Result
    childNodes foreach
    children (direct)
    firstChild nextSibling
    firstElementChild nextElementChild
    ChildNodes for (into variable)
    children-- (direct)
    ChildNodes for-- (into variable)
    ChildNodes for-- (direct)
    lastElementChild previousElementChild
    children-- (into variable)

    Fastest: N/A

    Slowest: N/A

Latest run results:
Run details: (Test run date: 6 months ago)
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36
Chrome 129 on Mac OS X 10.15.7
View result in a separate tab
Test name Executions per second
childNodes foreach 1870294.8 Ops/sec
children (direct) 2611374.2 Ops/sec
firstChild nextSibling 9245765.0 Ops/sec
firstElementChild nextElementChild 15010623.0 Ops/sec
ChildNodes for (into variable) 4653323.5 Ops/sec
children-- (direct) 4592751.5 Ops/sec
ChildNodes for-- (into variable) 2399889.0 Ops/sec
ChildNodes for-- (direct) 5971474.5 Ops/sec
lastElementChild previousElementChild 14791941.0 Ops/sec
children-- (into variable) 9820943.0 Ops/sec
LLMs can make mistakes. Check important info.
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