Function getParentAutoScrollElement

src/utils.js:432–456

(el, includeSelf)

function getParentAutoScrollElement(el, includeSelf) {
	// skip to window
	if (!el || !el.getBoundingClientRect) return getWindowScrollingElement();

	let elem = el;
	let gotSelf = false;
	do {
		// we don't need to get elem css if it isn't even overflowing in the first place (performance)
		if (elem.clientWidth < elem.scrollWidth || elem.clientHeight < elem.scrollHeight) {
			let elemCSS = css(elem);
			if (
				elem.clientWidth < elem.scrollWidth && (elemCSS.overflowX == 'auto' || elemCSS.overflowX == 'scroll') ||
				elem.clientHeight < elem.scrollHeight && (elemCSS.overflowY == 'auto' || elemCSS.overflowY == 'scroll')
			) {
				if (!elem.getBoundingClientRect || elem === document.body) return getWindowScrollingElement();

				if (gotSelf || includeSelf) return elem;
				gotSelf = true;
			}
		}
	/* jshint boss:true */
	} while (elem = elem.parentNode);

	return getWindowScrollingElement();
}

function extend(dst, src) {
	if (dst && src) {