Get offset relative to selector or window

offsetRelativeTo.js

/**
 * Get offset relative to selector (or window)
 *
 * @param {HTMLElement} el
 * @param {string|undefined} selector if not give, assumes root most (window)
 */
function offsetRelativeTo(el, selector) {
	let offsetTop = el.offsetTop;
	let offsetLeft = el.offsetLeft;
	let offsetParent = el.offsetParent;
	for (let index = 0; index < 100; index++) {
		if (!offsetParent) {
			// console.log("No more parents?");
			break;
		}
		offsetTop += offsetParent.offsetTop - offsetParent.scrollTop;
		offsetLeft += offsetParent.offsetLeft - offsetParent.scrollLeft;
		offsetParent = offsetParent.offsetParent;
		if (offsetParent && typeof selector !== "undefined" && offsetParent.matches(selector)) {
			// console.log("Found the parent!");
			break;
		}
	}
	return {
		top: offsetTop,
		left: offsetLeft,
	};
}