Get an elements X and Y position

getPosition.js

function getPosition(el) {
    let xPos = 0;
    let yPos = 0;

    while (el) {
        if (el.tagName == 'BODY') {
        // deal with browser quirks with body/window/document and page scroll
            const xScroll = el.scrollLeft || document.documentElement.scrollLeft;
            const yScroll = el.scrollTop || document.documentElement.scrollTop;

            xPos += (el.offsetLeft - xScroll + el.clientLeft);
            yPos += (el.offsetTop - yScroll + el.clientTop);
        } else {
        // for all other non-BODY elements
            xPos += (el.offsetLeft - el.scrollLeft + el.clientLeft);
            yPos += (el.offsetTop - el.scrollTop + el.clientTop);
        }

        el = el.offsetParent;
    }
    return {
        x: xPos,
        y: yPos,
    };
}