Benchmark: querySelector vs querySelectorAll vs getElementsByClassName vs getElementById

HTML Preparation code:

<div class="test2" id='2'></div>
<div class="test3" id='3'></div>
<div class="test"  id='0'></div>

Tests:

querySelector
document.querySelector(".test")
querySelectorAll
document.querySelectorAll(".test")
getElementsByClassName
document.getElementsByClassName("test")
getElementById
document.getElementById("0")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector
querySelectorAll
getElementsByClassName
getElementById

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; rv:94.0) Gecko/20100101 Firefox/94.0

Browser/OS: Firefox 94 on Windows

View result in a separate tab

Test name	Executions per second
querySelector	3738845.0 Ops/sec
querySelectorAll	1540853.8 Ops/sec
getElementsByClassName	7151239.0 Ops/sec
getElementById	6626049.5 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmark that compares the performance of four different DOM querying methods in Firefox 94 on Windows Desktop:

1. `document.querySelector`
2. `document.querySelectorAll`
3. `document.getElementsByClassName`
4. `document.getElementById`

These methods are used to select elements from an HTML document using their class, id, or other attributes.

**Methods Comparison**

The benchmark compares the performance of these four methods in different scenarios. Here's a brief overview of each method and its pros and cons:

1. **`document.querySelector`**:
	* Pros: Efficient and flexible way to select elements based on their class, id, or attribute.
	* Cons: Can be slower than other methods for very large datasets.
2. **`document.querySelectorAll`**:
	* Pros: Faster than `querySelector` for selecting multiple elements at once.
	* Cons: Returns a NodeList that requires additional processing to iterate over the results.
3. **`document.getElementsByClassName`**:
	* Pros: Faster than `querySelectorAll` when selecting elements by class name alone.
	* Cons: Slower than `querySelector` or `querySelectorAll` for more complex selections.
4. **`document.getElementById`**:
	* Pros: Fast and efficient way to select an element by its id attribute.
	* Cons: Only works if the element has a unique id, which may not always be the case.

**Library Usage**

None of the benchmark methods use any external libraries or frameworks.

**Special JS Features**

The benchmark uses standard JavaScript features such as DOM queries and HTML document structure. No special syntax or features are used beyond what is required for the DOM queries.

**Other Alternatives**

If you're interested in exploring alternative approaches, here are a few options:

1. **`document.querySelector` with attribute selectors**: Using `querySelector` with attribute selectors (e.g., `[class="test"]`) can be faster than using class names or ids.
2. **`CSS Selectors`**: Using CSS selectors (e.g., `.test`) can be even faster than DOM queries for selecting elements by class name alone.
3. **`Query Library` alternatives**: There are alternative query libraries available, such as `querySelectorAll`-style functions like `querySelectorAll`-like methods in the `cheerio` library, which may offer better performance or flexibility.

Keep in mind that these alternatives might require additional setup and configuration to work with your specific use case.

Related benchmarks:

querySelector vs querySelectorAll vs getElementsByClassName vs getElementById (version: 0)

Comparing performance of: querySelector vs querySelectorAll vs getElementsByClassName vs getElementById

Created: 3 years ago by: Guest

Jump to the latest result

querySelector

querySelectorAll

getElementsByClassName

getElementById

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):