Benchmark: Get element by id vs get elements by tag name

HTML Preparation code:

<html id="main" data-theme="dark"></html>

Tests:

Test get element by id
let el = document.getElementById('main')
Test get elements by tag name
let el = document.getElementsByTagName('html')[0]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Test get element by id
Test get elements by tag name

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Benchmark Definition:**

The website is comparing two approaches to retrieve an HTML element:

1. **Get element by id**: Using the `document.getElementById()` method to get an element with a specific ID, in this case, "main".
2. **Get elements by tag name**: Using the `document.getElementsByTagName()` method to get all HTML elements with a specific tag name, which is "html" in this case.

**Options being compared:**

* `document.getElementById()`: A DOM (Document Object Model) method used to retrieve an element by its ID.
* `document.getElementsByTagName()`: A DOM method used to retrieve a collection of HTML elements that match a specified tag name.

**Pros and Cons:**

1. **Get element by id**:
	* Pros:
		+ More efficient, as it only retrieves one element, regardless of the size of the document or the number of elements with the same ID.
		+ Less overhead compared to getting multiple elements.
	* Cons:
		+ Limited applicability, as not all HTML elements have a unique ID.
		+ May return `null` if no element is found with the specified ID.
2. **Get elements by tag name**:
	* Pros:
		+ Applicable in more situations, as most HTML elements have a unique tag name.
	* Cons:
		+ Less efficient, as it retrieves all matching elements, which can lead to slower performance if there are many elements with the same tag name.

**Library and purpose:**

There is no explicit library mentioned in this benchmark. However, `document` is an implicit reference to the DOM, which is a built-in JavaScript API for interacting with HTML documents.

**Special JS feature or syntax:**

None of the test cases utilize any special JavaScript features or syntax that would require explanation beyond the basic DOM methods.

**Other alternatives:**

For this specific benchmark, there aren't many alternative approaches. However, in general, when working with HTML elements:

* Using a CSS selector library like Sizzle (or its modern equivalent, CoreJS) can provide more efficient and flexible ways to select elements.
* Using a library like jQuery can simplify DOM manipulation and selection, but may add overhead due to the abstraction layer.

In this benchmark, the focus is on understanding the basic difference between retrieving an element by ID vs. getting all elements with a specific tag name, making it easy for developers to understand the trade-offs involved in each approach.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/115.0

Browser/OS: Firefox 115 on Linux

View result in a separate tab

Test name	Executions per second
Test get element by id	5076962.5 Ops/sec
Test get elements by tag name	2841890.0 Ops/sec

Related benchmarks:

Get element by id vs get elements by tag name (version: 0)

Comparing performance of: Test get element by id vs Test get elements by tag name

Created: one year ago by: Guest

Jump to the latest result

Test get element by id

Test get elements by tag name

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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