Benchmark: classList.contains vs. a

HTML Preparation code:

<div id="foo" class="bar baz"></div>

Script Preparation code:

var test_element = document.getElementById("foo");

Tests:

Add class
test_element.classList.add("bar");
Contains class
test_element.classList.contains("bar");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Add class
Contains class

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's being tested.

**Benchmark Overview**

The benchmark is designed to compare two approaches: using the `classList.contains()` method versus adding a class name directly using the `a` property (also known as "array-like indexing" or "numeric indexing").

**Options Compared**

There are two test cases:

1. **Add class**: This test adds a new class name to an element using `test_element.classList.add('bar')`. The `classList` API is used to manage classes, and it provides several benefits, including:
	* Fast and efficient class management.
	* Automatic handling of class inheritance.
	* Support for class names with multiple words (separated by hyphens).
2. **Contains class**: This test checks if an element has a specific class name using `test_element.classList.contains('bar')`. The `contains()` method provides:
	* Fast and efficient way to check for presence of a class.
	* Handling of class inheritance.
	* Support for class names with multiple words.

**Pros and Cons**

**Add Class (a)**

Pros:

* Provides direct access to the underlying array-like data structure, which can be beneficial in certain situations.
* Allows for more fine-grained control over class management.

Cons:

* Can be slower than using `classList` API due to the need to iterate through the class list.
* May lead to typos or incorrect class names if not used carefully.

**Contains Class (classList)**

Pros:

* Fast and efficient way to check for presence of a class.
* Handling of class inheritance is automatic, eliminating potential bugs.

Cons:

* Can be slower than using `a` property in certain situations due to the overhead of method calls.

**Library Used**

In this benchmark, the `classList` API is used, which is part of the HTML5 specification. It provides a more modern and efficient way to manage classes compared to the older `a` property approach.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax mentioned in the provided code snippet. However, it's worth noting that some newer browsers may use additional APIs or features to improve performance or provide better class management.

**Other Alternatives**

If you're interested in exploring other alternatives for managing classes, here are a few options:

* **CSS Class List API**: This is a more recent API (introduced in CSS3) that provides a way to manage classes using the `classList` property. It's similar to the `classList` API used in this benchmark but has some additional features and benefits.
* **Utility functions**: There are several utility libraries available, such as jQuery or Lodash, that provide functions for managing classes. These can be useful if you need more advanced class management capabilities.

Overall, the `classList` API is a recommended approach for managing classes in modern web development, offering a fast, efficient, and easy-to-use way to work with classes.

Related benchmarks:

classList.contains vs. a (version: 0)

Comparing performance of: Add class vs Contains class

Created: 4 years ago by: Guest

Jump to the latest result

Add class

Contains class

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):