Benchmark: querySelectorAll vs. Array.from(getElementsByClassName)

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")
getElementsByClassName
Array.from(document.getElementsByClassName(".test"))

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:

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.

Let's break down the benchmark and explain what's being tested.

**What is being tested?**

The benchmark compares two approaches to select multiple elements from an HTML document:

1. `document.querySelectorAll(".test")` (using the `querySelectorAll()` method)
2. `Array.from(document.getElementsByClassName("test"))`

Both methods aim to retrieve all elements with a class attribute containing "test".

**Options compared:**

The two options being compared are:

* **`querySelectorAll()`**: A DOM query API method that returns a NodeList, which is an array-like object of nodes.
* **`getElementsByClassName()`**: An older DOM method (introduced in IE 4) that returns a HTMLCollection, which is similar to an array but with some limitations.

**Pros and Cons:**

**`querySelectorAll()`**

Pros:

* More modern API
* Returns a NodeList, which is more flexible and powerful than a traditional array
* Works on most browsers (including modern web standards)

Cons:

* May be slower for small datasets due to the overhead of the DOM query algorithm

**`getElementsByClassName()`**

Pros:

* Older method that's still supported by older browsers
* Simpler implementation, potentially faster for small datasets

Cons:

* Returns a HTMLCollection, which is less powerful and more limited than a NodeList
* Less modern API, may not be as familiar to developers

**Library usage:**

The `Array.from()` function uses the ECMAScript 2015 (ES6) Array.prototype.from() method, which creates an array from an iterable. This library is part of the modern JavaScript standard.

**Special JS feature/syntax:**

This benchmark doesn't use any special features or syntax beyond ES6's `Array.from()` method. It only relies on standard JavaScript APIs and DOM methods.

**Other alternatives:**

If you wanted to compare other approaches, you could consider:

* Using CSS selectors instead of the DOM query API
* Comparing different iteration methods, such as using `for...of` loops or `forEach()`
* Using different data structures, like arrays or objects, for storing and manipulating the results

These alternatives would require additional test cases and modifications to the benchmark code.

Overall, this benchmark is designed to compare two common approaches to selecting multiple elements in an HTML document. By testing both methods, developers can gain insights into their performance characteristics and choose the best approach for specific use cases.

Related benchmarks:

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

Comparing performance of: querySelectorAll vs getElementsByClassName

Created: 5 years ago by: Guest

Jump to the latest result

querySelectorAll

getElementsByClassName

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):