Benchmark: getElementById vs querySelector vs getElementsByClassName vs getElementsByName 2

HTML Preparation code:

<div id="testdiv1">
  <div id="testdiv2" class="unique2" name="unique2" data-unique="2">test</div>
  <div id="testdiv3" class="unique3" name="unique3" data-unique="3">test</div>
</div>

Script Preparation code:

var i, imax;
var doc = document;

Tests:

getElementById
var test = doc.getElementById('testdiv2').innerHTML;
getElementsByClassName
var test = doc.getElementsByClassName('unique2')[0].innerHTML;
getElementsByName
var test = doc.getElementsByName('unique2')[0].innerHTML;
querySelectorAll
var test = doc.querySelectorAll("[data-unique='2']")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
getElementsByClassName
getElementsByName
querySelectorAll

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:86.0) Gecko/20100101 Firefox/86.0

Browser/OS: Firefox 86 on Windows

View result in a separate tab

Test name	Executions per second
getElementById	965400320.0 Ops/sec
getElementsByClassName	6526180.0 Ops/sec
getElementsByName	6459203.5 Ops/sec
querySelectorAll	1031766.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared options, pros and cons of each approach, and other considerations.

**What's being tested?**

The test measures the performance of different methods to retrieve a single DOM element:

1. `getElementById`
2. `getElementsByClassName`
3. `getElementsByName` (note: this is not a standard method in JavaScript; it might be a typo or a custom implementation)
4. `querySelectorAll`

**Options comparison**

Here's a brief overview of each option, their pros and cons:

1. **`getElementById`**
	* Pros:
		+ Fast and efficient
		+ Works well with IDs that are unique in the DOM
	* Cons:
		+ Can be slow if there are multiple elements with the same ID (e.g., due to inline styles or attributes)
		+ May not work correctly if the element is dynamically added or removed from the DOM
2. **`getElementsByClassName`**
	* Pros:
		+ Works well with classes that are unique in the DOM
		+ Can return an array of elements, which might be useful for further processing
	* Cons:
		+ Can be slower than `getElementById` due to the overhead of searching for matching class names
3. **`getElementsByName`** (assuming it's a custom implementation)
	* Pros: N/A (as it's not a standard method)
	* Cons: Unknown performance characteristics, potentially slow or inefficient due to the lack of standardization
4. **`querySelectorAll`**
	* Pros:
		+ Fast and efficient for simple selectors like `[data-unique='2']`
		+ Allows for more complex selectors, which might be useful in some cases
	* Cons:
		+ Can return an array of elements, which might not be what you want (depending on your use case)
		+ May have performance issues if the selector is too complex or matches many elements

**Library usage**

In this benchmark, `document` is used as a global variable to access the DOM. The `document` object provides various methods for interacting with the DOM, including `getElementById`, `getElementsByClassName`, and others.

**Special JS feature or syntax**

The test uses a custom attribute `data-unique` on one of the element's classes. This is not a standard HTML attribute and might be specific to this benchmark's use case. It's used as a selector in the `querySelectorAll` option.

**Other considerations**

When choosing an approach for retrieving a single DOM element, you should consider factors such as:

* Performance: How fast does the method need to be?
* Uniqueness: Are there multiple elements with the same ID or class name that might affect performance?
* Complexity: What kind of selectors are used in your use case (simple vs. complex)?
* Use case: Do you need to process the retrieved element further, or is it enough to just retrieve it?

**Alternatives**

Other methods for retrieving a single DOM element include:

* `getElementsByTagName`: Returns an array of elements with the specified tag name.
* `querySelector` and `querySelectorAll` (but with different selectors): These can be more complex than simple attribute-based selectors.

Keep in mind that each method has its own strengths and weaknesses, and the choice ultimately depends on your specific use case and performance requirements.

Related benchmarks:

getElementById vs querySelector vs getElementsByClassName vs getElementsByName 2 (version: 0)

Test performance of different ways of get just one particular DOM element

Comparing performance of: getElementById vs getElementsByClassName vs getElementsByName vs querySelectorAll

Created: 3 years ago by: Guest

Jump to the latest result

getElementById

getElementsByClassName

getElementsByName

querySelectorAll

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):