Scroll: Top / Bottom not working for iFrames, here's a script

[therksius]

A lot of the interfaces I work with use iframes, and they're quite long sometimes, and not being able to scroll to the bottom was infuriating. I made these two little custom scripts to help me out, figured someone else might benefit (only tested in Chrome).

(function scrollToTop() {
	const loopLimit = 1000;
	let workElem = document.activeElement, loopCount = 0;
	while (workElem) {
		if (loopCount++ > loopLimit) break;
		
		if (workElem.contentDocument?.activeElement) {
			workElem = workElem.contentDocument.activeElement;
			continue;
		}
		const scrollMem = workElem.scrollTop;
		workElem.scrollTop = 0;
		if (workElem.scrollTop !== scrollMem) break;
		workElem = workElem.parentElement;
	}
})();

(function scrollToBottom() {
	const loopLimit = 1000;
	let workElem = document.activeElement, loopCount = 0;
	while (workElem) {
		if (loopCount++ > loopLimit) break;
		
		if (workElem.contentDocument?.activeElement) {
			workElem = workElem.contentDocument.activeElement;
			continue;
		}
		const scrollMem = workElem.scrollTop;
		workElem.scrollTop = workElem.scrollHeight;
		if (workElem.scrollTop !== scrollMem) break;
		workElem = workElem.parentElement;
	}
})();

The break down is:
Define a loop limit to prevent any infinite loops.
Set the working element (workElem) to the document active element.
- If workElem is ever non-truthy, exit the loop.
- If workElem has a contentDocument (implying iframe), set to the active element WITHIN the contentDocument, restart loop.
Store/memorize the current scroll position (scrollMem).
Attempt to set the scroll position to top/bottom.
Now compare the scroll position with memorized position:
- If position changed, the element can scroll, and we're done: break
- Else, set workElem to it's parent element, restart loop