Benchmark: className vs classList

HTML Preparation code:

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

Tests:

className
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.className = "bar"; }
classList
var element = document.getElementById("foo"); var i = 1000; var cl = element.classList; while (i--) { cl.add("bar"); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
className
classList

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.

I'd be happy to explain the benchmark being measured on MeasureThat.net.

The benchmark is comparing two approaches for setting the class name of an HTML element:

1. **`className` property**: This approach uses the dot notation to set the class name of the element. The syntax `element.className = "bar"` sets the class name of the element to `"bar"`.
2. **`classList` property and its methods (add, addAll)**: This approach uses the `classList` property and its methods, such as `classList.add("bar")`, to set the class name of the element.

**Pros and Cons**

**`className` property:**

Pros:

* Simple and straightforward
* Most developers are familiar with this syntax

Cons:

* Can be slower due to the dot notation lookup
* May require more DOM queries (depending on the use case)

**`classList` property and its methods:**

Pros:

* Faster than the dot notation approach, as it uses a specialized data structure for class names
* Encourages explicit management of classes and reduces the need for DOM queries

Cons:

* Less familiar syntax, especially for older browsers or developers without recent training
* May require additional library support (in this case, the `classList` property is supported in modern browsers)

**Other Considerations**

The choice between these two approaches depends on the specific use case and performance requirements. If simplicity and familiarity are more important than raw performance, the dot notation approach might be preferred. However, if speed and explicit class management are critical, the `classList` property and its methods are likely a better choice.

**Library and Syntax**

In this benchmark, the library being used is not explicitly mentioned. However, it's worth noting that the `classList` property was introduced in HTML5 (2008) and became widely supported in modern browsers over time. The syntax `classList.add("bar")` has been part of the standard since then.

**Other Alternatives**

If you're interested in exploring alternative approaches or performance optimizations for setting class names, here are a few examples:

* Using a library like jQuery, which provides its own way of managing classes (e.g., `.addClass()`).
* Implementing custom DOM queries to set class names (e.g., using the `setAttribute()` method with the "class" attribute name).
* Investigating other performance-oriented approaches, such as memoization or caching class names.
* Considering alternative data structures for managing classes, like a hash table.

Keep in mind that these alternatives might not offer significant performance gains over the current best approach (using the `classList` property and its methods) but can be interesting to explore from a theoretical or optimization perspective.

Related benchmarks:

className vs classList (version: 0)

Comparing performance of: className vs classList

Created: 8 years ago by: Guest

Jump to the latest result

className

classList

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):