Benchmark: querySelectorAll vs getElementsByClassName vs live collection 2

HTML Preparation code:

<div id="root"></div>

Script Preparation code:

var el = document.getElementById('root');

for (let i = 0; i < 10000; i++) {
	const it = document.createElement('div');
  
  	it.className = 'item item-' + i;
  
  	el.appendChild(it)
}

var kek = el.getElementsByClassName("item");

Tests:

querySelectorAll
el.querySelectorAll(".item").item(0)
getElementsByClassName
el.getElementsByClassName("item").item(0)
live collection
kek.item(0)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelectorAll
getElementsByClassName
live collection

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

**What is being tested?**

The provided benchmark tests the performance of three different methods to retrieve elements from a DOM:

1. `querySelectorAll`
2. `getElementsByClassName`
3. `live collection` (which is actually an alias for `document.querySelectorAll`)

Each method is used in a separate test case, and the results are compared.

**Options being compared:**

* `querySelectorAll`: Returns all elements that match the specified selector.
	+ Pros: Fast and efficient, as it returns a single result object with a length property indicating the number of matched elements.
	+ Cons: May not be suitable for complex selectors or large numbers of elements, as it can lead to slower performance due to the DOM parsing overhead.
* `getElementsByClassName`: Returns all elements whose class attribute matches the specified value.
	+ Pros: Simple and efficient for simple use cases, but may not be suitable for complex scenarios, such as multiple classes or IDs.
	+ Cons: May return a large number of elements if the selector is too broad, leading to slower performance.
* `live collection` (alias for `document.querySelectorAll`): Returns all elements that match the specified selector, just like `querySelectorAll`.
	+ Pros: Fast and efficient, as it returns a single result object with a length property indicating the number of matched elements.
	+ Cons: May not be suitable for complex selectors or large numbers of elements, as it can lead to slower performance due to the DOM parsing overhead.

**Library and syntax considerations:**

* `document.getElementById` and `document.querySelector` are part of the W3C DOM API and are widely supported in modern browsers.
* `document.getElementsByClassName` is also part of the W3C DOM API and is widely supported, although it has some limitations compared to `querySelectorAll`.
* `live collection` (alias for `document.querySelectorAll`) uses a proprietary syntax that was introduced by Google Chrome as an extension to the W3C standard. It is now widely adopted in modern browsers.

**Pros and cons:**

| Method | Pros | Cons |
| --- | --- | --- |
| `querySelectorAll` | Fast, efficient, and suitable for most use cases | May not work well with complex selectors or large numbers of elements |
| `getElementsByClassName` | Simple and efficient for simple use cases | May return a large number of elements if the selector is too broad |
| `live collection` (alias for `document.querySelectorAll`) | Fast and efficient, but may have slower performance due to DOM parsing overhead | May not work well with complex selectors or large numbers of elements |

**Other alternatives:**

* For more complex use cases, alternative methods such as `querySelector` or `querySelectorAll` with a CSS selector can be used.
* For older browsers that don't support the W3C DOM API, other libraries or frameworks may need to be used.

In summary, the benchmark tests the performance of three different methods for retrieving elements from the DOM: `querySelectorAll`, `getElementsByClassName`, and `live collection` (alias for `document.querySelectorAll`). Each method has its pros and cons, and the choice of which one to use depends on the specific requirements of the project.

Related benchmarks:

querySelectorAll vs getElementsByClassName vs live collection 2 (version: 0)

Comparing performance of: querySelectorAll vs getElementsByClassName vs live collection

Created: 3 years ago by: Guest

Jump to the latest result

querySelectorAll

getElementsByClassName

live collection

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):