Benchmark: Fastest way to list children: childNodes vs children vs firstChild/nextSibling vs firstElementChild/nextElementSibling v2

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

Jump to the latest result

HTML Preparation code:

<html>

<body>
    <div id='test'>
        <div name='a'></div>
        <div name='b'></div>
        <div name='c'></div>
    </div>
</body>

</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

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

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

A JSON string with some data!

After removing the preamble, here's the actual data:

```
[
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 14791941.0,
        "TestName": "lastElementChild previousElementChild"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 9820943.0,
        "TestName": "children-- (into variable)"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 9245765.0,
        "TestName": "firstChild nextSibling"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 5971474.5,
        "TestName": "ChildNodes for-- (direct)"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 4653323.5,
        "TestName": "ChildNodes for (into variable)"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 4592751.5,
        "TestName": "children-- (direct)"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 2611374.25,
        "TestName": "children (direct)"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 2399889.0,
        "TestName": "ChildNodes for-- (into variable)"
    },
    {
        "RawUAString": "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",
        "Browser": "Chrome 129",
        "DevicePlatform": "Desktop",
        "OperatingSystem": "Mac OS X 10.15.7",
        "ExecutionsPerSecond": 14791941.0,
        "TestName": "lastElementChild previousElementChild"
    }
]
```

This appears to be a list of test results, with each item in the list representing a specific test case. The fields include:

* `RawUAString`: the raw UA string
* `Browser`: the browser name
* `DevicePlatform`: the device platform
* `OperatingSystem`: the operating system
* `ExecutionsPerSecond`: the number of executions per second
* `TestName`: the test name

Please let me know what you'd like to do with this data!

Latest run results:

Run details: (Test run date: one month ago)

User agent: 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

Browser/OS: 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

Related benchmarks:

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

Created: 3 years ago by: Guest

Jump to the latest 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)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):