Run results for: iframe traversal getElementsByTagName vs querySelectorAll w\ shadowroot traversal

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.5 Safari/605.1.15

Browser: Safari 26

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 months ago

finding a window in live collection

17.2M/s

finding a window with shadowroot handling

409K/s

View exact numbers

Test name	Executions per second
✓ finding a window in live collection	17,211,382 Ops/sec
finding a window with shadowroot handling	409,289 Ops/sec

HTML Preparation code:

<div>
</div>
<div>
  <iframe src="about: blank"></iframe>
</div>
<div>
  <iframe src="about: blank"></iframe>
</div>
<div>
  <template shadowrootmode="open">
    <style>
      body {
      	background-color: blue;
      }
    </style>
    <iframe src="about: blank"></iframe>
  </template>
</div>

Script Preparation code:

var iframeElementCollection = document.getElementsByTagName('iframe');
var findWindow = window.frames[0];

function isIframeElement(el) {
	return el.tagName === 'IFRAME';
}

function getAllIframes(from) {
	const iframes = [];

	for(const el of from.querySelectorAll('*')) {
		if(isIframeElement(el)) {
			iframes.push(el);
		} else if(el.shadowRoot) {
			iframes.push(...getAllIframes(el.shadowRoot));
		}
	}

	return iframes;
}

Tests:

finding a window in live collection
for(const iframeEl of iframeElementCollection) { if(findWindow === iframeEl.contentWindow) { return iframeEl; } }
finding a window with shadowroot handling
for(const iframeEl of getAllIframes(document.body)) { if(findWindow === iframeEl.contentWindow) { return iframeEl; } }