Benchmark: Has class className vs. classList

HTML Preparation code:

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

Tests:

className
var element = document.getElementById("foo"); var i = 1000; while (i--) { new RegExp('(^| )(one)( |$)', 'gi').test(element.className); }
setAttribute
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.classList.contains('one'); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
className
setAttribute

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 being tested, along with the pros and cons of each approach.

**What is being tested:**

The benchmark is comparing two approaches to check if an element has a class named "one" in its `className` property:

1. Using the `classList` API, which returns a `DOMTokenList` object that contains all classes applied to an element.
2. Using regular expressions to search for the string "one" within the `className` property.

**Options compared:**

The two options being compared are:

1. **classList**: This approach uses the `classList` API, which is a modern feature introduced in HTML5. It allows developers to efficiently check if an element has a particular class.
2. **Regular Expressions (RegExp)**: This approach uses regular expressions to search for the string "one" within the `className` property. Regular expressions can be powerful for pattern matching, but they can also be slow and resource-intensive.

**Pros and Cons of each approach:**

1. **classList**:
	* Pros:
		+ Fast and efficient.
		+ Modern feature that is widely supported in browsers.
		+ Allows developers to easily check for multiple classes using the `contains()` method.
	* Cons:
		+ Requires modern browsers that support HTML5.
2. **Regular Expressions (RegExp)**:
	* Pros:
		+ Can be used with older browsers that don't support the `classList` API.
		+ Allows developers to search for more complex patterns.
	* Cons:
		+ Can be slow and resource-intensive, especially for large classes or complex patterns.
		+ May not work as expected in some edge cases.

**Library and syntax:**

The benchmark uses the JavaScript `DOMTokenList` object, which is a part of the HTML5 specification. The `classList` property returns an instance of this object, which allows developers to efficiently check for classes using methods like `contains()`.

There are no special JavaScript features or syntax used in this benchmark that would require specialized knowledge.

**Other alternatives:**

If you prefer not to use the `classList` API, you could also use the `indexOf()` method on the `className` property to search for the class name:
```javascript
if (element.className.indexOf('one') !== -1) {
  // element has class "one"
}
```
However, this approach is slower and less efficient than using the `classList` API or regular expressions.

Overall, the benchmark provides a good test of two common approaches to checking for classes in HTML elements, allowing developers to compare performance and choose the best method for their use case.

Related benchmarks:

Has class className vs. classList (version: 0)

Comparing performance of: className vs setAttribute

Created: 7 years ago by: Guest

Jump to the latest result

className

setAttribute

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):