Benchmark: children vs new querySelctorAll

HTML Preparation code:

<div class="container">
  <ul>
    <li class="item">Item 1</li>
    <li class="item">Item 2</li>
    <li>Item 3</li>
  </ul>
</div>

Tests:

...children
const container = document.querySelector('.container > ul'); const itemList = [...container.children].filter(el => el.matches('li.item')); console.log(container, itemList);
querySelectorAll
const container = document.querySelector('.container > ul'); const itemList = document.querySelector('.container > ul > li.item'); console.log(container, itemList);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
...children
querySelectorAll

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:135.0) Gecko/20100101 Firefox/135.0

Browser/OS: Firefox 135 on Linux

View result in a separate tab

Test name	Executions per second
...children	134208.6 Ops/sec
querySelectorAll	158109.1 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark JSON and explain what's being tested.

**Benchmark Definition**

The benchmark is comparing two approaches to select an HTML list item:

1. `...children`: This approach uses the spread operator (`...`) to get all child elements of the `container` element, and then filters them using the `matches()` method.
2. `querySelectorAll`: This approach uses the `querySelectorAll()` method to directly select all elements that match the CSS selector `.container > ul > li.item`.

**Options Compared**

The two options are compared in terms of performance (measured as executions per second). The benchmark is interested in determining which approach is faster for this specific use case.

**Pros and Cons of Each Approach**

1. `...children`:
	* Pros: This approach can be more flexible, as it allows the filtering process to be performed on the child elements individually. It also avoids the potential performance overhead of using a CSS selector.
	* Cons: This approach may be slower due to the additional filtering step and the need to iterate over all child elements.
2. `querySelectorAll`:
	* Pros: This approach is likely to be faster, as it uses a single query to select multiple elements at once, which can reduce overhead.
	* Cons: This approach requires that the CSS selector matches exactly, and may not work if the HTML structure changes.

**Library Usage**

Neither of these approaches directly involves any JavaScript libraries. However, the `matches()` method is part of the W3C standard for CSS selectors, and is implemented in modern browsers.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntax used in this benchmark. The code is straightforward and follows conventional JavaScript practices.

**Other Considerations**

The benchmark assumes that the HTML structure matches the expected pattern (i.e., a container element with a child `ul` element containing multiple `li.item` elements). If the HTML structure changes, the results may be affected.

If you were to create similar benchmarks for other use cases, consider factors such as:

* The specific use case requirements (e.g., performance-critical vs. flexibility)
* The number of elements being filtered or queried
* The complexity of the CSS selector used

**Alternatives**

Some alternative approaches might include:

1. Using a library like Lodash to simplify filtering and iteration.
2. Using a more specialized library like jQuery for DOM manipulation and querying.
3. Implementing a custom filtering algorithm that leverages browser-specific APIs or WebAssembly for performance optimization.

However, for this specific use case, the two approaches being compared (using `...children` vs. `querySelectorAll`) are likely to provide sufficient insight into the trade-offs between flexibility and performance.

Related benchmarks:

children vs new querySelctorAll (version: 0)

Comparing performance of: ...children vs querySelectorAll

Created: 3 years ago by: Guest

Jump to the latest result

...children

querySelectorAll

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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