Benchmark: firstChild vs lastChild

HTML Preparation code:

<div id='box'></div>

Script Preparation code:

var box = document.getElementById('box');
    box.innerHTML = 'sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>s f</b>s df<p>df gsdfg sf g<b>'

Tests:

while firstChild removeChild firstChild
while (box.firstChild) { box.removeChild(box.firstChild); }
while firstChild removeChild lastChild
while (box.firstChild) { box.removeChild(box.lastChild); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
while firstChild removeChild firstChild
while firstChild removeChild lastChild

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser/OS: Chrome 128 on Windows

View result in a separate tab

Test name	Executions per second
while firstChild removeChild firstChild	1363653.4 Ops/sec
while firstChild removeChild lastChild	1097270.9 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll dive right in and explain the benchmark.

**Benchmark Overview**

The provided JSON represents two test cases, both measuring the performance of removing child nodes from an HTML element using different approaches: `firstChild` and `lastChild`.

**Benchmark Definition**

The benchmark definition is a JavaScript function that defines the operation to be performed. The first test case uses `while (box.firstChild) { box.removeChild(box.firstChild); }`, which repeatedly removes the first child node of the `box` element until it's empty. The second test case uses `while (box.lastChild) { box.removeChild(box.lastChild); }`, which does the same thing but for the last child node.

**Html Preparation Code**

The HTML preparation code is a simple `<div>` element with an ID of "box" that will be used as the target element for the benchmark operations.

**Individual Test Cases**

There are two individual test cases:

1. **while firstChild removeChild firstChild**: This test case measures the performance of removing child nodes using `firstChild`.
2. **while firstChild removeChild lastChild**: This test case measures the performance of removing child nodes using `lastChild`.

**Latest Benchmark Result**

The latest benchmark result shows the execution times for each test case:

1. **while firstChild removeChild firstChild**: 1363653.375 executions per second
2. **while firstChild removeChild lastChild**: 1097270.875 executions per second

These results suggest that removing child nodes using `firstChild` is slightly faster than removing them using `lastChild`.

**Performance Comparison**

To compare the performance of these two approaches, we can analyze why one might be slower than the other:

* Using `firstChild` to remove nodes may lead to more overhead due to the need to traverse the entire DOM tree from the root node down to find the first child.
* Using `lastChild` may be faster because it only requires traversing from the last node in the list of children back up to the parent element.

However, these are general observations and actual performance can vary depending on specific use cases and browser implementations.

**Conclusion**

In summary, this benchmark measures the performance of removing child nodes using `firstChild` and `lastChild`. The results suggest that `firstChild` is slightly faster than `lastChild`, but the difference is relatively small.

Related benchmarks:

firstChild vs lastChild (version: 0)

Comparing performance of: while firstChild removeChild firstChild vs while firstChild removeChild lastChild

Created: one year ago by: Guest

Jump to the latest result

while firstChild removeChild firstChild

while firstChild removeChild lastChild

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):