Benchmark: getElementById - MeasureThat.net

HTML Preparation code:

<div id="footer-info" class="clearfix test"></div>

Tests:

getElementById
var el = document.getElementById('footer-info');
getElementsByClassName
var el = document.getElementsByClassName('test');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
getElementsByClassName

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36

Browser/OS: Chrome 83 on Windows

View result in a separate tab

Test name	Executions per second
getElementById	3025370.2 Ops/sec
getElementsByClassName	2229492.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**What is tested?**

The provided benchmark tests the performance of two different methods to retrieve HTML elements: `getElementById` and `getElementsByClassName`. These are fundamental DOM manipulation techniques used extensively in web development.

**Options compared**

We have two test cases:

1. **`document.getElementById('footer-info')`**: This method retrieves an element by its ID, which is a unique identifier for the element.
2. **`document.getElementsByClassName('test')`**: This method retrieves all elements with a specific class name.

**Pros and Cons of each approach**

*   `getElementById`
    *   Pros:
        *   More efficient when you only need to retrieve one element by its ID.
        *   Less overhead since it doesn't require searching through multiple elements.
    *   Cons:
        *   Fails if there are multiple elements with the same ID (which is not a common scenario, but can happen).
*   `getElementsByClassName`
    *   Pros:
        *   Retrieves all matching elements, which can be useful for more complex queries or when you need to get all elements of a certain class.
        *   Less prone to issues due to multiple elements having the same ID (although this is rare).
    *   Cons:
        *   Can be slower since it requires searching through multiple elements.

**Library and its purpose**

In neither of the provided benchmark test cases are any libraries explicitly mentioned. The `document` object, which is part of the browser's DOM API, is used for both tests. However, if you were to use a library like jQuery or another framework that extends the DOM API, it might affect performance.

**Special JS feature or syntax**

There are no special features or syntaxes mentioned in these test cases. They focus on the basic functionality of `getElementById` and `getElementsByClassName`.

Now, let's take a look at some alternative approaches to consider:

*   **CSS Selectors**: Instead of using `document.getElementById` or `getElementsByClassName`, you can use CSS selectors like `#footer-info` or `.test`. This approach is often faster than the above methods since it relies on the browser's rendering engine, which is optimized for performance.
*   **QuerySelector API**: Modern browsers have introduced the `querySelector` and `querySelectorAll` methods as a part of their DOM API. These methods provide similar functionality to `document.getElementById` and `getElementsByClassName`, but are often faster due to improved caching and optimizations.

To write your own benchmark on MeasureThat.net, you would need to create a new benchmark definition with the same structure as provided in your example, including HTML preparation code and individual test cases.

Related benchmarks:

getElementById (version: 0)

Comparing performance of: getElementById vs getElementsByClassName

Created: 4 years ago by: Guest

Jump to the latest result

getElementById

getElementsByClassName

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):