Benchmark: querySelector vs. .children HTMLCollection

HTML Preparation code:

<div id="foo"></div>

Tests:

querySelector
let bar = document.body.querySelector("#id")
HTMLCollection .children
let bar = document.body.children.id

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector
HTMLCollection .children

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 2 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

The provided benchmark compares two approaches for selecting an element from an HTML document: `querySelector` and accessing an `HTMLCollection` directly via `.children.id`.

**What is tested?**

In this benchmark, two test cases are executed:

1. `let bar = document.body.querySelector("#id")`: This line of code uses the `querySelector` method to select an element with the id "id" from the HTML document.
2. `let bar = document.body.children.id`: This line of code accesses the `HTMLCollection` returned by `document.body.children`, and then selects the first element using the `id` property.

**Options compared**

The two approaches are compared in terms of their performance, which is measured in executions per second (`ExecutionsPerSecond`). The benchmark provides raw UAs (User Agents) data to help identify any browser-specific differences.

**Pros and Cons of each approach:**

1. **`querySelector`**
	* Pros:
		+ More modern and widely supported
		+ Returns a `NodeList` object, which is more flexible than an `HTMLCollection`
		+ Can be used with CSS selectors (not shown in this benchmark)
	* Cons:
		+ May incur additional overhead due to the parsing of CSS selectors
		+ Requires modern browsers that support the `querySelector` method
2. **Accessing `HTMLCollection` directly via `.children.id`**
	* Pros:
		+ Widely supported across older browsers and versions
		+ Can be faster in some cases, as it avoids the overhead of parsing CSS selectors
	* Cons:
		+ Returns an `HTMLCollection`, which can be less flexible than a `NodeList`
		+ May require more manual error handling for edge cases (e.g., when dealing with empty collections)

**Library and syntax considerations:**

In this benchmark, no libraries are used. However, if you were to extend this benchmark, you might want to consider using libraries like jQuery or Lodash, which provide additional utility functions for working with HTML collections.

There are no special JavaScript features or syntaxes being tested in this benchmark, other than the use of CSS selectors via `querySelector`.

**Alternative approaches:**

If you're interested in exploring alternative approaches, here are a few options:

1. **`getElementsByClassName`**: This method returns a NodeList containing elements that match the specified class name(s). While it's not used in this benchmark, it could be an interesting alternative to explore.
2. **`elementFromPoint`**: This method returns the element at the specified point on the page. While it's more complex than the approaches tested here, it could provide a more accurate representation of real-world use cases.
3. **Native methods**: Depending on your specific requirements, you might want to consider using native JavaScript methods like `requestAnimationFrame` or `Web Workers`, which can provide better performance and control over your benchmark.

I hope this explanation helps! If you have any further questions or would like me to elaborate on any of these points, feel free to ask.

Latest run results:

Run details: (Test run date: 15 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Windows

View result in a separate tab

Test name	Executions per second
querySelector	2802760.0 Ops/sec
HTMLCollection .children	2705420.0 Ops/sec

Related benchmarks:

querySelector vs. .children HTMLCollection (version: 0)

compare quse of querySelector("#id") to .children.id

Comparing performance of: querySelector vs HTMLCollection .children

Created: 15 days ago by: Registered User

Jump to the latest result

querySelector

HTMLCollection .children

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 2 days ago):