Benchmark: querySelector vs getElementsByClassName v3

HTML Preparation code:

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

Tests:

querySelectorAll
document.querySelector(".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 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36

Browser/OS: Chrome 66 on Windows 7

View result in a separate tab

Test name	Executions per second
querySelectorAll	2804327.5 Ops/sec
getElementsByClassName	3225618.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring the performance of two DOM query methods, `querySelector` and `getElementsByClassName`, is an interesting benchmark.

**What's being tested?**

The provided json represents a microbenchmark that compares the execution speed of two DOM query methods:

1. `document.querySelector(".test")`: This method returns the first element that matches the specified CSS selector.
2. `document.getElementsByClassName("test")`: This method returns all elements that match the specified class name.

**Options compared**

The benchmark is comparing the performance of these two methods, which are part of the Document Object Model (DOM) API in JavaScript.

**Pros and cons:**

* **`querySelector`**:
	+ Pros:
		- More efficient than `getElementsByClassName` for single-element queries.
		- Less memory-intensive as it returns only one element.
	+ Cons:
		- May not be as versatile as `getElementsByClassName` since it only returns the first matching element.
* **`getElementsByClassName`**:
	+ Pros:
		- Can return all elements that match a class name, making it more versatile than `querySelector`.
	+ Cons:
		- Returns all matching elements, which can be slower for single-element queries.

**Library and special JS feature**

There is no specific library mentioned in the benchmark definition. However, both methods are native DOM API functions, which means they don't rely on any external libraries to function.

**Special JS feature**

This benchmark doesn't explicitly use any special JavaScript features like async/await, Promises, or Web Workers. It's a simple microbenchmark that focuses on comparing the performance of two DOM query methods.

**Other alternatives**

If you wanted to add more test cases to this benchmark, some alternative approaches could be:

* Using `querySelectorAll` with a CSS selector that matches multiple elements.
* Comparing the performance of `querySelector` and `getElementsByClassName` for element manipulation operations like appending or removing child nodes.
* Adding test cases for other DOM query methods like `getElementById` or `getElementsByTagName`.
* Measuring the performance of different browser engines (e.g., Chrome, Firefox, Edge) to see how they compare in terms of DOM query performance.

These alternative approaches would allow you to further explore the performance characteristics of various DOM query methods and optimize your JavaScript code for better performance.

Related benchmarks:

querySelector vs getElementsByClassName v3 (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):