Benchmark: window.getComputedStyle vs. getBoundingClientRect width

HTML Preparation code:

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

Tests:

getComputedStyle
const x = window.getComputedStyle(document.getElementById('foo')).width
getBoundingClientRect
const x = document.getElementById('foo').getBoundingClientRect().width;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getComputedStyle
getBoundingClientRect

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Windows

View result in a separate tab

Test name	Executions per second
getComputedStyle	560075.1 Ops/sec
getBoundingClientRect	839326.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and considered.

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches: `window.getComputedStyle` and `getBoundingClientRect`. The goal is to determine which method is faster for retrieving the width of an element using a specific HTML structure.

**Options Compared**

Two options are being compared:

1. **`window.getComputedStyle`**: This method retrieves the computed style properties of an element, including its width.
2. **`getBoundingClientRect`**: This method returns the size and position of an element relative to the viewport.

**Pros and Cons of Each Approach**

* `window.getComputedStyle`:
	+ Pros:
		- Can retrieve all style properties, not just dimensions (width, height, etc.)
		- Can be used for more complex layout calculations
	+ Cons:
		- May incur additional overhead due to the need to parse and execute JavaScript code
		- May require more memory allocations, especially if dealing with large numbers of elements
* `getBoundingClientRect`:
	+ Pros:
		- Typically faster and more efficient than `getComputedStyle`
		- Returns only the dimensions (width, height) needed for this benchmark
	+ Cons:
		- Only returns dimensions, not all style properties
		- May not be suitable for complex layout calculations

**Library Usage**

There is no explicit library usage in this benchmark. However, the `document.getElementById` and `window.getComputedStyle` methods are part of the standard JavaScript API.

**Special JS Features or Syntax**

None are explicitly mentioned in this benchmark.

**Other Considerations**

* **Browser and Device**: The benchmark appears to be run on a desktop browser (Chrome 122) with Windows as the operating system.
* **Execution Frequency**: The test runs approximately 839,326 times per second for `getBoundingClientRect` and 560,075 times per second for `getComputedStyle`.

**Alternatives**

If you want to explore alternative approaches or libraries for measuring performance in JavaScript, here are some options:

1. **`requestAnimationFrame`**: This method allows you to schedule a callback function to be executed at the next available opportunity on the browser's event queue.
2. **Web Workers**: These allow you to run JavaScript code in separate threads, which can improve performance and scalability for CPU-intensive tasks.
3. **Libraries like Lighthouse** or **Benchmark.js**: These libraries provide built-in support for benchmarking and profiling JavaScript applications.

Keep in mind that the best approach will depend on your specific use case and requirements.

Related benchmarks:

window.getComputedStyle vs. getBoundingClientRect width (version: 0)

Comparing performance of: getComputedStyle vs getBoundingClientRect

Created: 2 years ago by: Guest

Jump to the latest result

getComputedStyle

getBoundingClientRect

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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