Benchmark: ClassList add vs className +=

HTML Preparation code:

<div id="one" class="firstClass secondClass"></div>

Script Preparation code:

var elem = document.getElementById("one");

Tests:

classList
elem.classList.add("Three");
className
elem.className += " Three";

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
classList
className

Fastest: N/A

Slowest: N/A

Latest 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 definition and test cases.

**Benchmark Definition**

The benchmark is designed to compare the performance of two ways to add a class to an HTML element:

1. `classList.add('Three')`
2. `elem.className += ' Three'`

**Options Compared**

In this benchmark, we have two options being compared:

* Option 1: Using the `classList` property to add a class.
* Option 2: Adding the class directly to the `className` attribute using string concatenation.

**Pros and Cons of Each Approach**

**Option 1: `classList.add('Three')`**

Pros:

* More concise and readable
* Often considered more efficient, as it uses an optimized native method
* Can be faster for larger classes

Cons:

* May not work correctly in older browsers or environments that don't support the `classList` property.
* Might require additional imports if using a library like jQuery.

**Option 2: `elem.className += ' Three'`**

Pros:

* Widely supported across browsers and environments
* Works with most JavaScript libraries and frameworks

Cons:

* Can be less readable due to the use of string concatenation
* May incur performance overhead for larger strings.
* Can lead to security vulnerabilities if not sanitized correctly.

**Library Used: `classList`**

The `classList` property is a part of the DOM API, introduced in HTML5. It allows elements to manage their own class list and provides methods like `add()`, `remove()`, and `contains()` to manipulate the classes. The benchmark likely uses this optimized native method to compare performance.

**Special JS Feature/ Syntax**

There are no special JavaScript features or syntax used in these test cases. They use standard JavaScript syntax and libraries (none mentioned).

**Other Alternatives**

If you wanted to add a class to an HTML element, some alternative approaches could be:

* Using `elem.classList.toggle('Three')`: This method toggles the presence of the class, which can be useful for managing dynamic class changes.
* Using a library like jQuery's `.addClass()` method: While not necessary here, it demonstrates another way to add classes in JavaScript.

**Benchmark Preparation Code**

The script preparation code sets up an HTML element with the ID "one" and assigns it to the `elem` variable. The HTML preparation code includes a `<div>` element with the specified attributes.

In summary, this benchmark compares the performance of two ways to add a class to an HTML element: using the optimized native `classList` property versus string concatenation for adding a class directly to the `className` attribute.

Related benchmarks:

ClassList add vs className += (version: 0)

Comparing performance of: classList vs className

Created: 5 years ago by: Guest

Jump to the latest result

classList

className

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):