Benchmark: className string concat vs classList

HTML Preparation code:

<div id='test'></div>

Script Preparation code:

var el = document.getElementById('test');

Tests:

className string concat
el.className = '1'; el.className = el.className + ' ' + '2';
classList add
el.className = '1'; el.classList.add('2');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
className string concat
classList add

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition JSON**

The website is testing two approaches for adding classes to an HTML element: concatenating strings using the `+` operator, and using the `classList.add()` method.

In the benchmark definition, we have two test cases:

1. `className string concat`: This test case creates an HTML element and sets its `className` property to `'1'`. Then, it appends a new class name `'2'` by concatenating strings.
2. `classList add`: This test case does the same as the previous one, but instead of concatenating strings, it uses the `classList.add()` method to add the new class.

**Comparison**

The benchmark is comparing two approaches:

* **String Concatenation**: Using the `+` operator to concatenate strings and set the `className` property.
* **classList.add()**: Using the `classList` API to add a class to the element.

**Pros and Cons**

**String Concatenation:**

Pros:

* Widely supported across browsers
* Simple and easy to understand

Cons:

* Can lead to performance issues due to string concatenation (e.g., inlining many small strings)
* May not be as efficient as `classList.add()` on modern browsers

**classList.add():**

Pros:

* More efficient than string concatenation, especially for large numbers of classes
* Less prone to performance issues due to string concatenation
* A part of the W3C DOM API and widely supported across browsers

Cons:

* May not be as widely supported in older browsers (pre-2010s)
* Can be less intuitive for some developers who are not familiar with the `classList` API

**Library**

In this benchmark, there is no explicit library mentioned. However, it's worth noting that the `classList` API is part of the W3C DOM specification and is widely supported across modern browsers.

**Special JS Feature or Syntax**

There isn't any special JavaScript feature or syntax mentioned in the benchmark definition. The test cases only use basic JavaScript syntax to create an HTML element and manipulate its properties.

**Other Alternatives**

If you're looking for alternative approaches, here are a few options:

* Using `addEventListener()` instead of `classList.add()`: Some older browsers (pre-2010s) support this approach.
* Using a library like jQuery or Lodash to simplify class manipulation: While not directly related to the benchmark, these libraries can provide additional functionality and abstraction for class management.

Keep in mind that the specific alternatives may depend on your use case, target browsers, and performance requirements.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:94.0) Gecko/20100101 Firefox/94.0

Browser/OS: Firefox 94 on Windows

View result in a separate tab

Test name	Executions per second
className string concat	1296660.8 Ops/sec
classList add	1087586.9 Ops/sec

Related benchmarks:

className string concat vs classList (version: 0)

className string concat vs classList 1. el.className = '1'; 2. add class '2' with string concat or classList add

Comparing performance of: className string concat vs classList add

Created: 2 years ago by: Guest

Jump to the latest result

className string concat

classList add

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):