Benchmark: 3 x getComputedStyle vs 2 x getComputedStyle + 1 x getBoundingClientRect

HTML Preparation code:

<div id="foo"></div>

Tests:

3 x getComputedStyle
var i = 5000; while (i--) { checkDisplay('foo'); } function checkDisplay(id) { const style = window.getComputedStyle(document.getElementById(id)); return style.height + style.marginTop + style.marginBottom }
2 x getComputedStyle + 1 x getBoundingClientRect
var i = 5000; while (i--) { checkDisplay('foo'); } function checkDisplay(id) { const el = document.getElementById(id); const style = window.getComputedStyle(el); const rect = el.getBoundingClientRect(); return rect.height + style.marginTop + style.marginBottom }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
3 x getComputedStyle
2 x getComputedStyle + 1 x getBoundingClientRect

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 the provided benchmark definition and test cases.

**Benchmark Definition**

The benchmark is comparing three approaches:

1. **3 x getComputedStyle**: This approach uses `window.getComputedStyle` to retrieve the style properties of an element three times in a loop.
2. **2 x getComputedStyle + 1 x getBoundingClientRect**: This approach uses `window.getComputedStyle` twice and `getBoundingClientRect` once in a loop.

**Options Compared**

The two approaches being compared are:

* Using `window.getComputedStyle` to retrieve style properties
* Using `getBoundingClientRect` to calculate element dimensions

**Pros and Cons of Each Approach**

1. **3 x getComputedStyle**:
	* Pros: This approach is simple and easy to understand.
	* Cons:
		+ It may involve more DOM queries, which can be slower than using `getBoundingClientRect`.
		+ The style properties are retrieved multiple times in a loop, which might incur additional overhead.
2. **2 x getComputedStyle + 1 x getBoundingClientRect**:
	* Pros: This approach reduces the number of DOM queries and avoids retrieving style properties multiple times in a loop.
	* Cons:
		+ It uses `getBoundingClientRect`, which may not be as accurate as using `window.getComputedStyle` for precise style calculations.
		+ The calculation involves combining two different methods, which might add complexity.

**Library and Its Purpose**

In both test cases, the `checkDisplay` function uses the following libraries:

* `document.getElementById`: used to retrieve an element by its ID
* `window.getComputedStyle`: used to retrieve the style properties of an element

The `getBoundingClientRect` method is not a library in itself but rather a built-in method on the DOMElement interface, which returns the size and position of an element relative to the viewport.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntaxes being used in these test cases. They are standard JavaScript code snippets that use native DOM methods.

**Other Alternatives**

If you were to optimize this benchmark further, you could consider the following alternatives:

* Using a CSS query API like `cssom` instead of `window.getComputedStyle`
* Caching the result of `getComputedStyle` or `getBoundingClientRect` to avoid recalculating it in each iteration
* Optimizing the loop and its operations using techniques like caching, memoization, or parallel processing

Keep in mind that the effectiveness of these alternatives depends on the specific use case and requirements.

Latest run results:

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

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/21A329 Twitter for iPhone/10.7

Browser/OS: Mobile Safari 17 on iOS 17.0

View result in a separate tab

Test name	Executions per second
3 x getComputedStyle	297.5 Ops/sec
2 x getComputedStyle + 1 x getBoundingClientRect	235.3 Ops/sec

Related benchmarks:

3 x getComputedStyle vs 2 x getComputedStyle + 1 x getBoundingClientRect (version: 0)

subj

Comparing performance of: 3 x getComputedStyle vs 2 x getComputedStyle + 1 x getBoundingClientRect

Created: one year ago by: Guest

Jump to the latest result

3 x getComputedStyle

2 x getComputedStyle + 1 x getBoundingClientRect

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):