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

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

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

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 2 months ago):