Benchmark: Selector performance 2

HTML Preparation code:

<div id='h'>Hello</div>
<div class='w'>World</div>
<div class='w'>!</div>

Tests:

id - getElementById
document.getElementById('h');
id - querySelector
document.querySelector('#h');
class - getElementsByClassName
document.getElementsByClassName('w');
class - querySelectorAll
document.querySelectorAll('.w');
tag - getElementsByTagName
document.getElementsByTagName('div');
tag - querySelectorAll
document.querySelectorAll('div');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
id - getElementById
id - querySelector
class - getElementsByClassName
class - querySelectorAll
tag - getElementsByTagName
tag - querySelectorAll

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

**Overview of MeasureThat.net**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The platform provides an environment for developers to compare the performance of different approaches to executing specific JavaScript code.

**Benchmark Definition JSON**

The provided benchmark definition JSON contains two main sections:

1. **Benchmark Setup**: This section defines the initial setup of the benchmark, including a script preparation code and an HTML preparation code. In this case, the script preparation code is empty, and the HTML preparation code creates a simple webpage with three div elements: `<div id='h'>Hello</div>`, `<div class='w'>World</div>`, and `<div class='w'>!</div>`. The purpose of this setup is to provide a consistent base for measuring the performance of different selectors.
2. **Individual Test Cases**: This section defines six individual test cases, each representing a specific selector or method for selecting elements from the HTML document.

**Test Cases and Selectors**

The six test cases are:

1. `id - getElementById`: Tests the `getElementById` method with an ID of `'h'`.
2. `id - querySelector`: Tests the `querySelector` method with an ID of `'h'`.
3. `class - getElementsByClassName`: Tests the `getElementsByClassName` method with a class name of `'w'`.
4. `class - querySelectorAll`: Tests the `querySelectorAll` method with a class name of `'w'`.
5. `tag - getElementsByTagName`: Tests the `getElementsByTagName` method with a tag name of `'div'`.
6. `tag - querySelectorAll`: Tests the `querySelectorAll` method with a tag name of `'div'`.

**Library and Syntax**

None of the test cases use a specific JavaScript library, but they do utilize standard JavaScript syntax for DOM manipulation.

**Pros and Cons of Different Approaches**

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

1. **`getElementById`**: Fastest, as it uses a direct lookup in the document's `elementById` cache.
	* Pros: Very fast
	* Cons: May not work if the element is dynamically generated or if there are multiple elements with the same ID
2. **`querySelector`**: Fast, but may require additional processing to select the desired element.
	* Pros: Can select multiple elements using a CSS selector
	* Cons: May be slower than `getElementById` for simple cases
3. **`getElementsByClassName`**: Slower, as it uses a cache lookup and can return multiple elements if there are multiple with the same class name.
	* Pros: Can select multiple elements
	* Cons: May be slower than `querySelector`
4. **`querySelectorAll`**: Slowest, as it uses a CSS selector and may require additional processing to parse the result.
	* Pros: Can select multiple elements using a CSS selector
	* Cons: May be slow for simple cases
5. **`getElementsByTagName`**: Fast, but only suitable for selecting elements by tag name.
	* Pros: Very fast
	* Cons: Limited to selecting elements by tag name

**Other Considerations**

When choosing an approach, consider the following factors:

* Speed: If performance is critical, `getElementById` or `getElementsByClassName` may be a better choice. However, if you need to select multiple elements, `querySelectorAll` might be more suitable.
* Flexibility: If you need to select elements using different class names or IDs, `querySelector` or `querySelectorAll` might be a better choice.

**Alternatives**

If MeasureThat.net is not available, other alternatives for benchmarking JavaScript performance include:

1. **Benchmark.js**: A popular benchmarking library for JavaScript.
2. **js-benchmark**: A simple and lightweight benchmarking library for JavaScript.
3. **Google's Perf Kit**: A set of tools for measuring the performance of web applications.

These alternatives can be used to create custom benchmarks or to compare the performance of different approaches in a controlled environment.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36

Browser/OS: Chrome 75 on Linux

View result in a separate tab

Test name	Executions per second
id - getElementById	3082223.5 Ops/sec
id - querySelector	1861489.6 Ops/sec
class - getElementsByClassName	2987928.0 Ops/sec
class - querySelectorAll	908795.7 Ops/sec
tag - getElementsByTagName	3045801.8 Ops/sec
tag - querySelectorAll	1011366.9 Ops/sec

Related benchmarks:

Selector performance 2 (version: 0)

Comparing performance of: id - getElementById vs id - querySelector vs class - getElementsByClassName vs class - querySelectorAll vs tag - getElementsByTagName vs tag - querySelectorAll

Created: 5 years ago by: Guest

Jump to the latest result

id - getElementById

id - querySelector

class - getElementsByClassName

class - querySelectorAll

tag - getElementsByTagName

tag - querySelectorAll

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):