Benchmark: querySelectorAll vs getElementsByTagName iteration2

HTML Preparation code:

<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>

Tests:

querySelectorAll
for (const div of document.querySelectorAll('div'));
getElementsByTagName
for (const div of document.getElementsByTagName('div'));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelectorAll
getElementsByTagName

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.6 Safari/605.1.15

Browser/OS: Safari 16 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
querySelectorAll	892734.8 Ops/sec
getElementsByTagName	1035458.3 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition:**

MeasureThat.net is testing two ways to iterate over elements in an HTML document:

1. `document.querySelectorAll('div')`: This method returns a NodeList of all elements that match the CSS selector `'div'`.
2. `document.getElementsByTagName('div')`: This method returns a collection of DOM elements with the tag name `'div'`.

Both methods are used to loop through each element in the document and execute some code.

**Options compared:**

The benchmark is comparing two options:

1. **`querySelectorAll`**: Uses the CSS selector syntax to select elements, which can be more efficient than using `getElementsByTagName` because it's faster and more flexible.
2. **`getElementsByTagName`**: Uses the DOM element name (`'div'`) directly, which can lead to slower performance due to the overhead of using a tag name.

**Pros and Cons:**

* **`querySelectorAll`**:
	+ Pros:
		- Faster execution times due to the optimized CSS selector algorithm.
		- More flexible, as it allows for more complex selectors.
	+ Cons:
		- May require additional browser support for older versions of browsers that don't implement CSS selectors efficiently.
* **`getElementsByTagName`**:
	+ Pros:
		- Guaranteed compatibility with all modern browsers that support the DOM.
	+ Cons:
		- Slower execution times due to the overhead of using a tag name.

**Library and Purpose:**

There is no explicit library mentioned in this benchmark. However, both `querySelectorAll` and `getElementsByTagName` are part of the Document Object Model (DOM) API, which is a standard interface for interacting with web pages in JavaScript.

**Special JS feature or syntax:**

None of the provided code uses any special JavaScript features or syntax that require explanation.

**Other alternatives:**

If you want to explore other options for iterating over elements in an HTML document, here are a few alternatives:

* **`querySelector`**: A more modern alternative to `getElementsByTagName`, which allows for more complex selectors and is generally faster.
* **`Array.prototype.forEach()`**: A JavaScript method that can be used to iterate over arrays (or DOM elements) using a callback function. While not directly related to HTML, it's a common technique for iterating over collections.

For this benchmark, the choice between `querySelectorAll` and `getElementsByTagName` will depend on your specific use case and performance requirements. If you need high-performance iteration over simple element selection, `querySelectorAll` might be the better choice. However, if compatibility with older browsers is essential, `getElementsByTagName` might be a safer option.

Related benchmarks:

querySelectorAll vs getElementsByTagName iteration2 (version: 0)

Comparing performance of: querySelectorAll vs getElementsByTagName

Created: one year ago by: Guest

Jump to the latest result

querySelectorAll

getElementsByTagName

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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