Benchmark: getComputedStyle vs window.innerWidth

HTML Preparation code:

<style>body {--breakpoint: "md";}</style>

Tests:

getComputedStyle
getComputedStyle(document.body) .getPropertyValue("--breakpoint") .replace(/\W/g, "") === "md"
window.innerWidth
window.innerWidth === 700

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getComputedStyle
window.innerWidth

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/123.0.0.0 Safari/537.36 Zaap3.6.8

Browser/OS: Chrome 123 on Windows

View result in a separate tab

Test name	Executions per second
getComputedStyle	897651.1 Ops/sec
window.innerWidth	1691546.6 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.

**Overview**

The provided JSON represents a JavaScript microbenchmark test case created on MeasureThat.net. The test measures the performance difference between two approaches: using `getComputedStyle` to access a CSS variable and comparing it with directly accessing `window.innerWidth`.

**What is being tested?**

1. **`getComputedStyle(document.body).getPropertyValue("--breakpoint") .replace(/\\W/g, "") === "md"`**: This test case measures the performance of accessing the `--breakpoint` CSS variable using `getComputedStyle`. The code extracts the value of the variable, removes any non-word characters from it (using a regular expression), and checks if its value is equal to `"md"`.
2. **`window.innerWidth === 700`**: This test case measures the performance of directly accessing the `window.innerWidth` property.

**Comparison options**

The two approaches being compared are:

1. Using `getComputedStyle` to access a CSS variable (Test Case 1)
	* Pros:
		+ Allows for dynamic access to CSS variables, which can be useful in various scenarios.
		+ Can provide more accurate results if the variable's value changes dynamically.
	* Cons:
		+ May introduce additional overhead due to the DOM query and property access.
2. Directly accessing `window.innerWidth` (Test Case 2)
	* Pros:
		+ Typically faster, as it only involves a simple property access.
	* Cons:
		+ Only returns the value of `window.innerWidth`, which might not be useful in all scenarios.

**Other considerations**

* The use of CSS variables (`--breakpoint`) is a relatively new feature introduced in CSS3. It allows for more flexible and dynamic styling, but also introduces additional complexity.
* The `Zaap3.6.8` string in the benchmark result suggests that the test is using a caching mechanism or some optimization technique to improve performance.

**Library and its purpose**

The `getComputedStyle` method is part of the Web APIs, specifically designed for accessing computed styles on an element.

**Special JS feature or syntax (not applicable)**

There are no special JavaScript features or syntaxes mentioned in this benchmark. The test only uses standard JavaScript language constructs.

**Alternatives**

Some alternative approaches to measuring performance could include:

1. Using a library like `fast-assert` or `expect` to compare values directly.
2. Measuring the execution time of different implementations using tools like `Benchmark.js`.
3. Comparing the performance of different rendering engines (e.g., Blink, Gecko) using a tool like `RenderMonkey`.

Keep in mind that the best approach depends on the specific use case and requirements.

Related benchmarks:

getComputedStyle vs window.innerWidth (version: 3)

Comparing performance of: getComputedStyle vs window.innerWidth

Created: 2 years ago by: Registered User

Jump to the latest result

getComputedStyle

window.innerWidth

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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