Benchmark: JS selectors getters

HTML Preparation code:

<div id="idElement" class="classElement" role="dialog"></div>

Tests:

querySelector ID
var el = document.querySelector('#idElement'); var className = el.className;
querySelector CLASS
var el = document.querySelector('.classElement'); var className = el.className;
querySelector ATTR
var el = document.querySelector('[role=dialog]'); var className = el.className;
getElementById
var el = document.getElementById('idElement'); var className = el.className;
getElementsByClassName
var el = document.getElementsByClassName('classElement')[0]; var className = el.className;
getElementsByTagName
var el = document.getElementsByTagName('DIV')[0]; var className = el.className;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector ID
querySelector CLASS
querySelector ATTR
getElementById
getElementsByClassName
getElementsByTagName

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0

Browser/OS: Firefox 91 on Ubuntu

View result in a separate tab

Test name	Executions per second
querySelector ID	2192551.5 Ops/sec
querySelector CLASS	2105646.5 Ops/sec
querySelector ATTR	1029619.9 Ops/sec
getElementById	2479026.0 Ops/sec
getElementsByClassName	1713252.4 Ops/sec
getElementsByTagName	1756070.9 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark.

**What is being tested?**

MeasureThat.net is testing the performance of different JavaScript methods for selecting and manipulating HTML elements in a web page. Specifically, it's comparing six different approaches:

1. `document.getElementById('idElement')`
2. `document.querySelector('#idElement')`
3. `document.querySelector('.classElement')`
4. `document.querySelector('[role=dialog]')`
5. `document.getElementsByClassName('classElement')[0]`
6. `document.getElementsByTagName('DIV')[0]`

These methods are used to retrieve an HTML element based on its id, class, or attribute value.

**Options compared**

Each test case compares the performance of a single JavaScript method against others. The options being compared include:

* DOM query methods: `getElementById`, `querySelector`, `querySelector` with classes and attributes, `getElementsByClassName`, and `getElementsByTagName`
* Different types of selectors: id, class, attribute value
* Different usage patterns: retrieving an element by its ID vs. its class or attribute value

**Pros and cons**

Here's a brief overview of the pros and cons of each approach:

1. **`document.getElementById('idElement')`**
	* Pros: Fast and reliable for selecting elements by their unique id.
	* Cons: May not work if multiple elements have the same id (although this is rare).
2. **`document.querySelector('#idElement')`** and **`document.querySelector('.classElement')`**
	* Pros: Flexible and powerful, allowing for CSS selectors to be used.
	* Cons: Can be slower than `getElementById` due to the overhead of parsing CSS selectors.
3. **`document.querySelector('[role=dialog]')`**
	* Pros: Efficiently selects elements based on their attribute value.
	* Cons: May not work if multiple elements have the same role.
4. **`document.getElementsByClassName('classElement')[0]`**
	* Pros: Fast and reliable for selecting elements by class name.
	* Cons: Returns an array of elements, so indexing is required to access a single element.
5. **`document.getElementsByTagName('DIV')[0]`**
	* Pros: Efficiently selects elements based on their tag name.
	* Cons: May not work if multiple elements have the same tag name.

**Libraries and special features**

In this benchmark, none of the test cases use external libraries or special JavaScript features like async/await or Promises. However, it's worth noting that some browsers may use internal APIs to optimize DOM query performance.

**Other considerations**

When writing performance-critical code, consider the following factors:

* Use the most efficient DOM query method for your specific use case.
* Avoid using overly complex CSS selectors or unnecessary attribute values.
* Optimize your HTML structure and layout to reduce DOM query overhead.
* Consider caching or memoizing results from expensive DOM queries.

**Alternatives**

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

1. **Vanilla.js alternatives**: Use other JavaScript libraries like jQuery, Lodash, or Ramda to optimize your code.
2. **Modern DOM query methods**: Explore newer methods like `document.querySelectorAll()` and `document.querySelector()` with CSS selectors.
3. **Experimental APIs**: Keep an eye on emerging features like Web APIs for optimized DOM querying.

Keep in mind that the performance differences between these alternatives may vary depending on the specific use case and browser implementation.

Related benchmarks:

JS selectors getters (version: 0)

Comparing performance of: querySelector ID vs querySelector CLASS vs querySelector ATTR vs getElementById vs getElementsByClassName vs getElementsByTagName

Created: 3 years ago by: Guest

Jump to the latest result

querySelector ID

querySelector CLASS

querySelector ATTR

getElementById

getElementsByClassName

getElementsByTagName

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):