Benchmark: getElementsByTagName vs querySelectorAll

HTML Preparation code:

<ul id="list">
  <li>Item 1</li>
  <li>Item 2</li>
  <li>Item 3</li>
  <li>Item 4</li>
</ul>

Script Preparation code:

const list = document.getElementById('list')

Tests:

getElementsByTagName
list.getElementsByTagName('li');
QueryselectorAll
list.querySelectorAll('li')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementsByTagName
QueryselectorAll

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36

Browser/OS: Chrome 144 on Windows

View result in a separate tab

Test name	Executions per second
getElementsByTagName	20391402.0 Ops/sec
QueryselectorAll	3499075.0 Ops/sec

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 defines two test cases:

1. `getElementsByTagName`: Tests the performance of the `getElementsByTagName` method, which is used to get an HTMLCollection of elements with a specific tag name (in this case, "li").
2. `QueryselectorAll`: Tests the performance of the `querySelectorAll` method, which is used to get an NodeList of elements that match a CSS selector (in this case, `"li"`).

**Options Compared**

The benchmark compares two approaches:

1. **getElementsByTagName**: This approach uses the `getElementsByTagName` method to retrieve the elements. It's a traditional and widely supported method for getting HTML elements.
2. **QueryselectorAll**: This approach uses the `querySelectorAll` method to retrieve the elements. It's a more modern and flexible alternative to `getElementsByTagName`.

**Pros and Cons**

Here are some pros and cons of each approach:

* **getElementsByTagName**
	+ Pros: Widely supported, easy to use, and well-documented.
	+ Cons: Can be slower than `querySelectorAll` for larger datasets, as it returns an HTMLCollection which is not optimized for performance.
* **QueryselectorAll**
	+ Pros: Faster than `getElementsByTagName` for larger datasets, more flexible, and modern.
	+ Cons: May not work in older browsers that don't support CSS selectors.

**Library/Feature Used**

In this benchmark, the following library feature is used:

* **CSS selectors**: The `querySelectorAll` method uses CSS selectors to match elements. In this case, `"li"` is used as a selector.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes mentioned in this benchmark.

**Other Alternatives**

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

* **getElementsByClassName**: This method returns an HTMLCollection of elements with the specified class name. It's similar to `getElementsByTagName`, but can be faster for larger datasets.
* **querySelector**: This method returns a NodeList of elements that match the specified CSS selector. It's similar to `querySelectorAll`, but returns a single element instead of a collection.

**Additional Considerations**

When choosing between these approaches, consider the following factors:

* Browser support: If you need to support older browsers, `getElementsByTagName` might be a better choice.
* Performance: For larger datasets, `QueryselectorAll` and `getElementsByClassName` can be faster than `getElementsByTagName`.
* Flexibility: `QueryselectorAll` is more flexible than `getElementsByTagName`, as it allows for more complex selectors.

I hope this explanation helps!

Related benchmarks:

getElementsByTagName vs querySelectorAll (version: 0)

Comparing performance of: getElementsByTagName vs QueryselectorAll

Created: 4 years ago by: Registered User

Jump to the latest result

getElementsByTagName

QueryselectorAll

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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