Highlight HTML emergents on mouseover.js

function highlight(highlightedElement) {
	var restore = []

	const oldRadius = highlightedElement.style.borderRadius
	const oldShadow = highlightedElement.style.boxShadow
	restore.push(() => {highlightedElement.style.borderRadius = oldRadius; highlightedElement.style.boxShadow = oldShadow})
	highlightedElement.style.borderRadius = "1px"
	highlightedElement.style.boxShadow = "0 0 0 4px white , 2px 2px 10px 4px rgba(0, 0, 0, 0.39)"

	const timer = setTimeout(function() {
		var element = highlightedElement
		var parent = element.parentNode
		while (parent != null) {
			for (let sibling of parent.childNodes) {
				if (sibling != element && sibling instanceof HTMLElement) {
					const oldFilter = sibling.style.filter
					restore.push(() => {sibling.style.filter = oldFilter;})
					sibling.style.filter += " blur(5px)"
				}
			}
			element = parent
			parent = element.parentNode
		}
	}, 2000);
	restore.push(()=> clearTimeout(timer) )

	return () => restore.forEach(f=>f())
}
let removePreviousHighlight = () => {};
document.body.addEventListener('mouseover', mouseOver);
function mouseOver(event) {
	removePreviousHighlight();
	removePreviousHighlight = highlight(event.target);
}