Benchmark: hasAttribute vs classList

HTML Preparation code:

<p id="foo" class="foo" data-foo></p>

Tests:

hasAttribute
const el = document.getElementById("foo"); let i = 10000; while (i--) { if (el.classList.contains('foo')) { const foo = 'foo'; } }
classList
const el = document.getElementById("foo"); let i = 10000; while (i--) { if (el.hasAttribute("data-foo")) { const foo = 'foo'; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
hasAttribute
classList

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's break down the provided JSON data for the JavaScript microbenchmark.

**Benchmark Overview**

The benchmark is designed to compare two approaches for checking if an element has a specific attribute: using `classList.contains()` and using `hasAttribute()`. The goal is to determine which approach is faster, more efficient, or both.

**Options Being Compared**

Two options are being compared:

1. **`classList.contains('foo')`**: This method checks if the element with the ID "foo" has a class attribute named "foo".
2. **`el.hasAttribute("data-foo")`**: This method checks if the element with the ID "foo" has an attribute named "data-foo".

**Pros and Cons of Each Approach**

1. **`classList.contains('foo')`**
	* Pros:
		+ More intuitive and readable, as it explicitly specifies what class to check for.
		+ May be faster if the element's class list is large, as it only needs to iterate over a subset of classes.
	* Cons:
		+ Can be slower on smaller class lists or when iterating over multiple classes, due to the method's overhead.
2. **`el.hasAttribute("data-foo")`**
	* Pros:
		+ Faster, as it only checks if the attribute exists without requiring class iteration.
	* Cons:
		+ Less intuitive and less readable, as it requires understanding of the `hasAttribute()` method's behavior.
		+ May be slower on elements with many attributes due to the method's overhead.

**Library Used**

The benchmark uses the `classList` API, which is a part of the HTML5 specification. The `classList` property returns a `DOMTokenList` object that provides methods for manipulating class lists. In this case, `contains()` is used to check if an element has a specific class.

**Special JavaScript Feature/Syntax**

The benchmark uses a modern JavaScript feature: template literals (`\r\nconst foo = 'foo';\r\n`). Template literals are a way to create strings with embedded expressions using the `\` character. This feature was introduced in ECMAScript 2015 (ES6) and is widely supported by modern browsers.

**Other Alternatives**

If you want to compare these approaches, you could also consider:

1. Using `el.getAttribute("data-foo")` instead of `el.hasAttribute("data-foo")`. This would allow you to check if the attribute has a specific value.
2. Implementing your own class iteration solution using `for...in` or `forEach()` loops.
3. Comparing performance with different browser versions, as older browsers may have different optimizations for these methods.

By considering these alternatives, you can gain a deeper understanding of the trade-offs involved in choosing between these approaches and optimize your code accordingly.

Related benchmarks:

hasAttribute vs classList (version: 0)

Comparing performance of: hasAttribute vs classList

Created: 3 years ago by: Guest

Jump to the latest result

hasAttribute

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):