Benchmark: getElementById vs querySelector vs getElementsByClassName....

HTML Preparation code:

<div id="testdiv">
  <div id="unique" class="unique" name="unique" data-unique="1">test</div>
</div>

Script Preparation code:

var i, imax;
var doc = document;

Tests:

getElementById
var test = doc.getElementById('unique');
getElementsByTagName
var test = doc.getElementsByTagName('div')[1];
querySelector
var test = doc.querySelector('#unique');
getElementsByClassName
var test = doc.getElementsByClassName('unique')[0];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
getElementsByTagName
querySelector
getElementsByClassName

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.142 Safari/537.36

Browser/OS: Chrome 75 on Windows

View result in a separate tab

Test name	Executions per second
getElementById	2299565.5 Ops/sec
getElementsByTagName	1478469.6 Ops/sec
querySelector	850291.1 Ops/sec
getElementsByClassName	1518004.0 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript microbenchmark test case on MeasureThat.net. The benchmark tests the performance of different methods for retrieving a specific DOM element.

**Options being compared:**

1. `getElementById`
2. `getElementsByTagName`
3. `querySelector`
4. `getElementsByClassName`

**Pros and Cons of each approach:**

* `getElementById`: This method uses an ID selector to retrieve the first element that matches the specified value. It is generally fast and efficient, as it only needs to traverse a small subset of the DOM tree.
	+ Pros: Fast, reliable, and widely supported.
	+ Cons: May not work if multiple elements have the same ID.
* `getElementsByTagName`: This method uses a tag name selector to retrieve all elements with a specific tag name. It returns an array of matching elements.
	+ Pros: Flexible, as it can match multiple elements at once.
	+ Cons: Can be slower than `getElementById` due to the need to traverse more DOM nodes.
* `querySelector`: This method uses a CSS selector expression to retrieve the first element that matches the specified criteria. It is similar to `getElementById`, but provides more flexibility and power in terms of selecting elements.
	+ Pros: Flexible, fast, and widely supported.
	+ Cons: May be slower than `getElementById` for very simple selectors.
* `getElementsByClassName`: This method uses a class name selector to retrieve all elements with a specific class name. It returns an array of matching elements.
	+ Pros: Flexible, as it can match multiple elements at once.
	+ Cons: Can be slower than `getElementById` due to the need to traverse more DOM nodes.

**Library usage:**

None of the test cases explicitly use any libraries or frameworks. However, MeasureThat.net itself is a browser-based testing framework that provides a consistent and controlled environment for running JavaScript benchmarks.

**Special JS feature or syntax:**

* No specific features or syntax are used in these test cases.
* `MeasureThat.net` uses its own custom testing framework, which is not open-sourced.

**Other alternatives:**

If you're interested in writing your own benchmarking tests, there are several alternatives to MeasureThat.net:

1. Browser benchmarks like **Speedometer 2**, **Benchmark.js**, or **Fast.js**
2. Online platforms like **jsPerf** (now deprecated) or **TestRunner.io**
3. Command-line tools like **Benchmark** or **bml**

Keep in mind that each of these alternatives may have their own strengths and weaknesses, and some may be more suitable for specific use cases than others.

In conclusion, the test case provided measures the performance of four different methods for retrieving a single DOM element: `getElementById`, `getElementsByTagName`, `querySelector`, and `getElementsByClassName`. Each approach has its pros and cons, and the choice of method depends on the specific requirements and constraints of your project.

Related benchmarks:

getElementById vs querySelector vs getElementsByClassName.... (version: 0)

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

Comparing performance of: getElementById vs getElementsByTagName vs querySelector vs getElementsByClassName

Created: 5 years ago by: Guest

Jump to the latest result

getElementById

getElementsByTagName

querySelector

getElementsByClassName

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):