Benchmark: querySelectorAll.forEach vs. Array.from(getElementsByClassName).forEach

HTML Preparation code:

<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>

Tests:

querySelectorAll
document.querySelectorAll(".test").forEach(function (el) { el.remove() })
getElementsByClassName
Array.from(document.getElementsByClassName(".test")).forEach(function (el) { el.remove() })

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelectorAll
getElementsByClassName

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.101 Safari/537.36

Browser/OS: Chrome 91 on Windows

View result in a separate tab

Test name	Executions per second
querySelectorAll	1114925.6 Ops/sec
getElementsByClassName	1116432.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and their pros and cons.

**Benchmark Overview**

The provided benchmark compares two approaches to remove all elements with a specific class from an HTML document using JavaScript:

1. `querySelectorAll` (using the DOM query API)
2. `getElementsByClassName` (using the DOM method)

**Options Compared**

The two options being compared are:

1. **querySelectorAll**: This method uses the Document Object Model (DOM) to select elements based on a CSS selector.
2. **getElementsByClassName**: This method uses the DOM to get all elements with a specific class name.

**Pros and Cons of Each Approach**

### QuerySelectorAll

Pros:

* Fast and efficient, especially for large datasets
* Returns an HTMLCollection, which is optimized for iteration
* Supports more advanced selectors (e.g., attributes, pseudo-classes)

Cons:

* Requires a valid CSS selector syntax
* Can be slower if the selector is complex or ambiguous
* May not work well with older browsers that don't support the DOM query API

### getElementsByClassName

Pros:

* Simple and intuitive to use, especially for removing elements based on class name
* Works in older browsers that don't support the DOM query API
* Returns an HTMLCollection, which is optimized for iteration

Cons:

* Can be slower than QuerySelectorAll, especially for large datasets
* May not work well with complex selectors or attributes

**Library and Purpose**

In this benchmark, `Array.from()` is used to convert the HTMLCollection returned by `getElementsByClassName` into an array-like object that can be iterated over. The purpose of using `Array.from()` is to provide a more modern and efficient way to iterate over the elements.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntax used in this benchmark beyond what's standard for DOM manipulation.

**Other Considerations**

1. **Browser Support**: The benchmark uses Chrome 91 as the test browser, which may not be representative of other browsers.
2. **Platform**: The benchmark runs on a desktop platform, which may affect performance compared to mobile or web platforms.
3. **Test Environment**: The benchmark assumes an optimal test environment with no additional overhead or interference.

**Other Alternatives**

If you're looking for alternative approaches to remove elements from an HTML document, consider:

1. Using `querySelector` (similar to QuerySelectorAll but returns a single element instead of an HTMLCollection).
2. Using `forEach` on the document body or a container element to iterate over all elements.
3. Using a library like jQuery that provides its own way of selecting and manipulating DOM elements.

Keep in mind that each approach has its pros and cons, and the choice ultimately depends on your specific use case and requirements.

Related benchmarks:

querySelectorAll.forEach vs. Array.from(getElementsByClassName).forEach (version: 0)

Comparing performance of: querySelectorAll vs getElementsByClassName

Created: 3 years ago by: Guest

Jump to the latest result

querySelectorAll

getElementsByClassName

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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