Benchmark: class vs data- querySelector vs getElementsByClassName

HTML Preparation code:

<div class="test"></div>
<div data-test="1"></div>

Tests:

querySelector
document.querySelector(".test")
getElementsByClassName
document.getElementsByClassName('[data-test="1"]')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector
getElementsByClassName

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.64 Safari/537.36

Browser/OS: Chrome 101 on Linux

View result in a separate tab

Test name	Executions per second
querySelector	4662051.0 Ops/sec
getElementsByClassName	5675642.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is tested, the options compared, their pros and cons, and other considerations.

**Benchmark Definition**

The benchmark defines two test cases:

1. `document.querySelector(".test")`: This test case uses the `querySelector` method to select an element with a class of "test" within the HTML document.
2. `document.getElementsByClassName('[data-test="1"]')`: This test case uses the `getElementsByClassName` method to get an array of elements that have a `data-test` attribute with the value "1".

**Options Compared**

The two test cases compare the performance of:

* `querySelector` (CSS selector-based)
* `getElementsByClassName` (class name-based)

**Pros and Cons**

* `querySelector`:
	+ Pros: More flexible and powerful, allowing for more complex selections using CSS selectors.
	+ Cons: May be slower due to the complexity of the selector syntax.
* `getElementsByClassName`:
	+ Pros: Simpler and faster, with fewer possibilities for errors or performance issues.
	+ Cons: Less flexible, requiring a fixed class name.

**Other Considerations**

* **Library:** Neither test case uses a library. However, if a library were used, it would likely provide additional functionality or optimizations.
* **Special JS feature or syntax:** There is no special JavaScript feature or syntax being tested in this benchmark.

**Alternatives**

Other alternatives for selecting elements include:

* `getElementsByTagName`: selects elements by their tag name (e.g., "div")
* `getElementById`: selects an element by its ID
* `querySelectorAll`: selects multiple elements using a CSS selector

These alternatives may have different performance characteristics and use cases compared to `querySelector` and `getElementsByClassName`.

**Benchmark Preparation Code**

The provided HTML preparation code creates two elements:

* `<div class="test"></div>`: This element will be used by the `querySelector` test case.
* `<div data-test="1"></div>`: This element will be used by the `getElementsByClassName` test case.

The script preparation code is empty, indicating that no JavaScript code needs to be executed before running the benchmark.

Related benchmarks:

class vs data- querySelector vs getElementsByClassName (version: 0)

Comparing performance of: querySelector vs getElementsByClassName

Created: 3 years ago by: Guest

Jump to the latest result

querySelector

getElementsByClassName

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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