Benchmark: querySelector vs getElementsByClassName v33

HTML Preparation code:

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

Tests:

querySelectorAll
document.querySelectorAll(".test")
getElementsByClassName
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

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark is designed to compare the performance of two DOM querying methods in JavaScript:

1. `document.querySelectorAll(".test")`
2. `document.getElementsByClassName("test")`

Both methods are used to retrieve an array of HTML elements with a specific class name (`"test"`).

**Options Compared**

In this case, we have only two options being compared:

* `document.querySelector()` (not explicitly listed in the benchmark definition, but implied by its usage)
* `getElementsByClassName()`
* `querySelectorAll()`

However, it's worth noting that `querySelector()` and `getElementsByClassName()` are often used interchangeably, as they both return a single element or an array of elements matching the specified selector. The main difference is that `querySelector()` stops at the first match, while `getElementsByClassName()` returns all matches.

**Pros and Cons**

Here's a brief summary of each approach:

* **`document.querySelector()`**: Fast and efficient for selecting a single element. However, it only returns the first matching element, so if you need to retrieve multiple elements, this might not be suitable.
	+ Pros: Fast, lightweight
	+ Cons: Only returns one element, may require multiple calls for multiple elements
* **`getElementsByClassName()`**: Returns all elements with the specified class name. This can be useful when you need to retrieve multiple matching elements.
	+ Pros: Returns all matching elements, can be used for selecting multiple elements at once
	+ Cons: Can be slower than `querySelector()` due to the overhead of returning an array of results
* **`querySelectorAll()`**: Similar to `getElementsByClassName()`, but more flexible and powerful. It uses CSS selectors and can match complex patterns.
	+ Pros: Flexible, powerful, returns all matching elements
	+ Cons: Can be slower than `querySelector()` due to the overhead of returning an array of results

**Library/Utility**

In this benchmark, none of the methods explicitly use a library or utility. However, it's worth noting that both `querySelectorAll()` and `getElementsByClassName()` are part of the DOM API, which is a fundamental part of the web platform.

**Special JS Feature/Syntax**

There doesn't appear to be any special JavaScript feature or syntax being tested in this benchmark.

**Other Alternatives**

If you're looking for alternative methods to query the DOM, here are some options:

* **`forEach()`**: Instead of using `querySelectorAll()`, you can use `document.querySelectorAll(".test").forEach()` to iterate over an array of elements.
* **`Array.prototype.map()`**: You can also use `document.querySelectorAll(".test").map((element) => element.textContent)` to retrieve the text content of each element.

Keep in mind that these alternatives might have different performance characteristics and use cases compared to the original methods being benchmarked.

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3521.0 Safari/537.36

Browser/OS: Chrome 70 on Mac OS X 10.13.6

View result in a separate tab

Test name	Executions per second
querySelectorAll	697384.6 Ops/sec
getElementsByClassName	2715617.0 Ops/sec

Related benchmarks:

querySelector vs getElementsByClassName v33 (version: 0)

Comparing performance of: querySelectorAll vs getElementsByClassName

Created: 6 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 28 days ago):