Benchmark: DOM selector benchmark about class, data attribute

HTML Preparation code:

<div class="bar" data-value="true"></div>
<div class="bar" data-value="true"></div>
<div class="bar" data-value="true"></div>
<div class="bar" data-value="true"></div>
<div class="bar" data-value="false"></div>
<div class="bar" data-value="true"></div>
<div class="bar" data-value="false"></div>
<div class="bar" data-value="false"></div>
<div class="bar" data-value="true"></div>
<div class="bar" data-value="true"></div>

Tests:

class
const $selector = document.querySelectorAll('.bar'); $selector.forEach(element => { if (JSON.parse(element.dataset.value)) { console.log(element.dataset.value); } });
data attribute
const $selector = document.querySelectorAll('[data-value="true"]'); $selector.forEach(element => { console.log(element.dataset.value); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
class
data attribute

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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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 and explain what is tested, the different approaches compared, their pros and cons, and other considerations.

**Benchmark Definition**

The provided benchmark definition represents a JavaScript microbenchmark that tests two approaches: using CSS class selectors and using data attributes to filter DOM elements. The benchmark aims to measure which approach is faster for this specific use case.

**Options Compared**

There are two test cases:

1. **Class**: This approach uses the `document.querySelectorAll('.bar')` method to select all elements with the class "bar", and then iterates through the resulting NodeList using a `forEach` loop to log the value of the `data-value` attribute.
2. **Data Attribute**: This approach uses the `[data-value="true"]` pseudo-class to select all elements that have a `data-value` attribute set to `"true"`, and then iterates through the resulting NodeList using a `forEach` loop to log the value of the `data-value` attribute.

**Pros and Cons**

* **Class Approach**: Pros:
	+ More widely supported by older browsers.
	+ Can be used for more complex selection scenarios (e.g., multiple classes).
Cons:
	+ May be slower due to the need to use the `querySelectorAll()` method, which can be slower than using a pseudo-class.
* **Data Attribute Approach**: Pros:
	+ Faster, as it uses a pseudo-class that is optimized by modern browsers for performance.
	+ More concise and easier to read.
Cons:
	+ Requires the `data-value` attribute to be set on each element, which may not always be possible or desirable.

**Library**

None of the provided benchmark code uses any external libraries.

**Special JS Feature or Syntax**

The `forEach` loop is a standard JavaScript feature. However, it's worth noting that some older browsers (e.g., Internet Explorer 9) had issues with `forEach`, which led to polyfills being created for this purpose.

**Other Considerations**

* **Browser Support**: The benchmark assumes that the browser supports modern CSS pseudo-classes and the `data` attribute. Older browsers may not support these features, which could affect the results.
* **Optimization**: Some browsers (e.g., Chrome) have optimization techniques in place to improve performance for specific use cases, such as the `classList` API or native web worker support.

**Alternatives**

If you were to recreate this benchmark, you might consider adding additional test cases to cover other approaches, such as:

* Using a library like Lodash or jQuery to perform the filtering.
* Using a different data structure, such as an array or Set, instead of a NodeList.
* Adding more complex selection scenarios or filtering conditions.

Keep in mind that optimizing performance-critical code requires thorough testing and analysis, taking into account various browser differences and optimizations.

Related benchmarks:

DOM selector benchmark about class, data attribute (version: 1)

Comparing performance of: class vs data attribute

Created: 5 years ago by: Registered User

Jump to the latest result

class

data attribute

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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