Benchmark: ownerDocument.defaultView vs window.getComputedStyle

HTML Preparation code:

<div id="root"><div>

Script Preparation code:

var el = document.getElementById("root");
function getStyle(elem){
  var view = elem.ownerDocument.defaultView;
  if ( !view || !view.opener ) {
    view = window;
  }

  return view.getComputedStyle( elem );
}

function getStyle2(elem){
  return window.getComputedStyle( elem );
}

Tests:

ownerDocument.defaultView
var computedStyle = getStyle(el);
window.getComputedStyle
var computedStyle = getStyle2(el);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
ownerDocument.defaultView
window.getComputedStyle

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/117.0.0.0 Safari/537.36

Browser/OS: Chrome 117 on Windows

View result in a separate tab

Test name	Executions per second
ownerDocument.defaultView	732782.1 Ops/sec
window.getComputedStyle	1064090.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is being tested.

**Benchmark Definition**

The benchmark defines two different approaches to retrieve the computed style of an HTML element:

1. `ownerDocument.defaultView`: This approach uses the `ownerDocument` property to access the default view, which is the top-level window object associated with a document. It then uses the `getComputedStyle()` method of this view to retrieve the computed style.
2. `window.getComputedStyle`: This approach directly uses the `window.getComputedStyle()` method to retrieve the computed style.

**Options Compared**

The two options are being compared in terms of performance, specifically:

* `ownerDocument.defaultView`: This option may provide an advantage in certain cases where the window object is not available or is not associated with a valid document. However, it's unclear whether this will be relevant for most use cases.
* `window.getComputedStyle`: This is a widely used and well-established method for retrieving computed styles.

**Pros and Cons**

1. `ownerDocument.defaultView`:
	* Pros: May provide an advantage in certain edge cases or when the window object is not available.
	* Cons: May be slower or less reliable due to the additional check and potential overhead of accessing the owner document.
2. `window.getComputedStyle`:
	* Pros: Widely supported, well-established, and generally fast.
	* Cons: None notable.

**Library/Functionality**

The benchmark uses two JavaScript functions:

1. `getStyle()`: This function is defined in the "Script Preparation Code" section of the benchmark definition. It returns the computed style of an element using either `ownerDocument.defaultView` or `window.getComputedStyle`, depending on whether a valid window object is available.
2. `getStyle2()`: This function is also defined in the "Script Preparation Code" section and simply calls `window.getComputedStyle()` to retrieve the computed style.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax used in this benchmark, only standard ES5 JavaScript.

**Other Alternatives**

Alternative approaches could include:

1. Using a CSS DOM adapter library like `css-dom` to provide a standardized API for accessing computed styles.
2. Implementing a custom solution using a combination of DOM and window object manipulation techniques.
3. Using a framework or library that provides a high-level interface for working with styles, such as React or Angular.

Keep in mind that these alternatives would likely introduce additional complexity and potential overhead compared to the simple `window.getComputedStyle` approach used in this benchmark.

Related benchmarks:

ownerDocument.defaultView vs window.getComputedStyle (version: 0)

Comparing performance of: ownerDocument.defaultView vs window.getComputedStyle

Created: 8 years ago by: Registered User

Jump to the latest result

ownerDocument.defaultView

window.getComputedStyle

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):