Benchmark: DataAttribute vs Class Selector vs ID Selector vs getElementById vs getElementsByClassName

HTML Preparation code:

<div class="hello" id="hello" data-hello>Hello</div>

Tests:

Class
document.querySelector('.hello');
ID
document.querySelector('#hello');
data attribute
document.querySelector('[data-hello]');
getElementById
document.getElementById('hello');
getElementsByClassName
document.getElementsByClassName('hello')[0];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Class
ID
data attribute
getElementById
getElementsByClassName

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark measures the performance of different ways to select an HTML element in JavaScript. The test cases use the `document.querySelector()` method, which is a modern way to select elements based on their class, ID, or attribute values.

**Test Cases**

There are five test cases:

1. **Class**: `document.querySelector('.hello');`
2. **ID**: `document.querySelector('#hello');`
3. **Data Attribute**: `document.querySelector('[data-hello]');`
4. **getElementById**: `document.getElementById('hello');` (note: this is a deprecated method)
5. **getElementsByClassName**: `document.getElementsByClassName('hello')[0];`

**Comparison of Selection Methods**

Here's a brief comparison of the different selection methods:

* **Class**: Uses the class list to select elements. This method is fast because it only needs to iterate over the element's class list.
	+ Pros: Fast, modern way to select elements.
	+ Cons: May not work well if there are many classes or complex class selectors.
* **ID**: Uses a unique ID to select an element. This method is also fast because it can use a single database lookup to find the matching element.
	+ Pros: Fast, can be used with HTML attributes like `id`.
	+ Cons: Limited by the availability of unique IDs in the document.
* **Data Attribute**: Uses a data attribute (e.g., `data-hello`) to select elements. This method is gaining popularity because it allows for more flexible and reusable selectors.
	+ Pros: Flexible, can be used with HTML attributes like `data-`.
	+ Cons: May not work well if there are many data attributes or complex selectors.
* **getElementById**: Uses a unique ID to select an element (just like the class method). However, this method is deprecated because it's less flexible than the other methods.
	+ Pros: Fast, can be used with HTML attributes like `id`.
	+ Cons: Limited by the availability of unique IDs in the document, and deprecated.

**Library Used**

In this benchmark, none of the libraries are explicitly mentioned. However, if we consider popular JavaScript libraries that provide similar functionality to the selection methods, we might think of:

* Lodash (for its `class` method): `_.class(element)`
* jQuery (for its `$()` function, which is essentially a shortcut for `document.querySelector()` with class or ID selectors)
* CSS Selector APIs (e.g., `querySelectorAll()`, `matchSelector()`) which provide more advanced selection methods.

**Special JS Features/Syntax**

This benchmark does not use any special JavaScript features or syntax. All the test cases rely on standard JavaScript and HTML elements.

**Other Alternatives**

If you need to select elements in a different way, some alternative approaches might include:

* Using `DOMParser` to parse an XML string and select elements
* Using `HTMLParser` to parse an HTML string and select elements
* Using a CSS preprocessor like Sass or Less to write custom class selectors
* Using a library like Sizzle (the engine behind jQuery's `$()` function)

Keep in mind that the choice of selection method depends on your specific use case, performance requirements, and personal preference.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:120.0) Gecko/20100101 Firefox/120.0

Browser/OS: Firefox 120 on Windows

View result in a separate tab

Test name	Executions per second
Class	3306890.5 Ops/sec
ID	3291698.8 Ops/sec
data attribute	3107549.0 Ops/sec
getElementById	5293324.0 Ops/sec
getElementsByClassName	3393544.0 Ops/sec

Related benchmarks:

DataAttribute vs Class Selector vs ID Selector vs getElementById vs getElementsByClassName (version: 0)

Comparing performance of: Class vs ID vs data attribute vs getElementById vs getElementsByClassName

Created: one year ago by: Guest

Jump to the latest result

Class

ID

data attribute

getElementById

getElementsByClassName

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):