Benchmark: id vs class - MeasureThat.net

HTML Preparation code:

<div id="1" class="2">

Tests:

id
const value = document.getElementById("1").innerHtml;
class
const value = document.getElementsByClassName("2").innerHtml;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
id
class

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 23 days ago):

LLMs can make mistakes. Check important info.

Let's break down what's being tested on the provided JSON.

The test cases are designed to compare the performance of accessing DOM elements using either an `id` or a `class`. In this case, the HTML string has an `id` and a `class` attribute, which is used in the benchmark definitions.

**Options compared:**

1. **`id`**: Using the `document.getElementById()` method to access the element.
2. **`class`**: Using the `document.getElementsByClassName()` method to access the elements with the specified class.

**Pros and Cons of each approach:**

* **`id`**:
	+ Pros: More efficient, as there's only one element with the given `id`, reducing the search space for the browser.
	+ Cons: If you need to select multiple elements, this method can become less efficient due to DOM traversal overhead.
* **`class`**:
	+ Pros: Easier to select multiple elements at once and reduces unnecessary DOM traversal.
	+ Cons: Can be slower if there are many elements with the same class, as the browser needs to filter through the results.

In general, using `id`s can lead to better performance for single-element selections, while `class` selections might be better suited when you need to select multiple elements.

**Library and purpose:**

The `document.getElementById()` and `document.getElementsByClassName()` methods are part of the W3C DOM API (Document Object Model) and are used to retrieve elements in a web page's document. The former is designed for single-element selection, while the latter allows retrieving multiple elements that match a specific class.

**Special JavaScript feature or syntax:**

There doesn't seem to be any special features or syntax being tested here.

**Other considerations:**

Keep in mind that these benchmarks are focused on performance and may not account for other factors like browser caching, rendering, or layout calculations. The results might also depend on the specific use case and requirements of your application.

If you need alternative approaches, some options could be:

1. **CSS Selectors:** You can use CSS selectors to access elements with specific classes or IDs.
2. **QuerySelectorAll() method:** This method returns a NodeList of all matching elements in the document, which can provide better performance for multiple element selections.
3. **Native JavaScript methods:** Depending on your browser and version, you might have access to native JavaScript methods like `Array.from()` or `Array.prototype.filter()` for more efficient array-like selection.

However, these alternatives would require changes to your benchmark definitions and test cases.

The current test case is well-designed, providing a clear comparison between accessing elements using `id` vs. `class`.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:103.0) Gecko/20100101 Firefox/103.0

Browser/OS: Firefox 103 on Linux

View result in a separate tab

Test name	Executions per second
id	2315829.0 Ops/sec
class	1441006.8 Ops/sec

Related benchmarks:

id vs class (version: 0)

Comparing performance of: id vs class

Created: 2 years ago by: Guest

Jump to the latest result

id

class

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 23 days ago):