1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

const isScrollable = function (ele) {
    const hasScrollableContent = ele.scrollHeight > ele.clientHeight;

    const overflowYStyle = window.getComputedStyle(ele).overflowY;
    const isOverflowHidden = overflowYStyle.indexOf('hidden') !== -1;

    return hasScrollableContent && !isOverflowHidden;
};

const getScrollableParent = function (ele) {
    return !ele || ele === document.body
        ? document.body
        : isScrollable(ele)
        ? ele
        : getScrollableParent(ele.parentNode);
};