Benchmark: offsetTop pref - MeasureThat.net

HTML Preparation code:

<div id="el">
  <h2>Lorem ipsum dolor sit amet</h2>
</div>

Script Preparation code:

var el = document.getElementById("el");

Tests:

getBoundingClientRect
el.getBoundingClientRect()
offsetTop
el.offsetTop

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getBoundingClientRect
offsetTop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:126.0) Gecko/20100101 Firefox/126.0

Browser/OS: Firefox 126 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
getBoundingClientRect	4544576.5 Ops/sec
offsetTop	15372505.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided JSON data and explain what's being tested, compared, and other considerations.

**Benchmark Definition**

The benchmark definition is represented by two main sections:

1. **Script Preparation Code**: This code is used to prepare the JavaScript script that will be executed during the benchmark. In this case, it retrieves an HTML element using `document.getElementById("el")`. The variable `el` refers to the retrieved element.
2. **Html Preparation Code**: This code is used to create the HTML structure that will be used as input for the benchmark. In this case, a simple `<div>` element with an ID of "el" is created.

**Test Cases**

The test cases are defined in the following JSON array:

```json
[
    {
        "Benchmark Definition": "el.getBoundingClientRect()",
        "Test Name": "getBoundingClientRect"
    },
    {
        "Benchmark Definition": "el.offsetTop",
        "Test Name": "offsetTop"
    }
]
```

Here, we have two test cases:

1. `getBoundingClientRect`: This test case measures the performance of calling `el.getBoundingClientRect()` on the retrieved element.
2. `offsetTop`: This test case measures the performance of accessing the `offsetTop` property directly on the retrieved element.

**Comparison**

The comparison being made here is between calling `getBoundingClientRect()` and directly accessing the `offsetTop` property. Both approaches have different pros and cons:

* **Calling `getBoundingClientRect()```**: This approach:
	+ Provides more context about the element's position (x, y, width, height) in a single call.
	+ Can be useful for layout-related calculations or when you need to consider multiple dimensions of an element.
	However, it may incur additional overhead due to the need to create and populate a bounding box structure.
* **Directly accessing `offsetTop```**: This approach:
	+ Is typically faster since it only requires accessing a single property value.
	+ Does not provide as much context about the element's position compared to calling `getBoundingClientRect()`.
	However, it may require more calls if you need to access multiple properties (e.g., `offsetLeft`, `offsetWidth`, etc.).

**Library**

None of the test cases use any external libraries. The tests are self-contained and only rely on standard JavaScript DOM APIs.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax used in these test cases. They only use standard JavaScript and DOM APIs.

**Other Alternatives**

If you need to compare different approaches to accessing element positions, some other alternatives could include:

* Using `getBoundingClientRect()` with the `client` option set to `false`, which returns a bounding box that does not include layout margins.
* Using `getBoundingClientRect()` with the `layoutMode` option set to `1`, which returns a bounding box that includes layout margins.
* Using a library like Lodash or Moment.js to create and manipulate bounding boxes.

Keep in mind that the choice of approach depends on your specific use case, performance requirements, and personal preference.

Related benchmarks:

offsetTop pref (version: 0)

Comparing performance of: getBoundingClientRect vs offsetTop

Created: 3 years ago by: Guest

Jump to the latest result

getBoundingClientRect

offsetTop

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):