web-ui-pack/helpers/findScrollParent.js

Web package with UI elements

function hasFixedPos(el) {
    const p = el.style.position;
    const n = "fixed";
    return p === n || (!p && window.getComputedStyle(el).position === n);
}
export default function findScrollParent(el) {
    const p = el.parentElement;
    if (!p) {
        return null;
    }
    if (p.scrollTop > 0 || p.scrollLeft > 0) {
        return p;
    }
    const orig = p.onscroll;
    p.onscroll = (e) => {
        e.stopImmediatePropagation();
    };
    let prev = p.scrollTop;
    p.scrollTop += 10;
    if (prev !== p.scrollTop) {
        p.scrollTop = prev;
        setTimeout(() => (p.onscroll = orig), 1);
        return p;
    }
    prev = p.scrollLeft;
    p.scrollLeft += 10;
    if (prev !== p.scrollLeft) {
        p.scrollLeft = prev;
        setTimeout(() => (p.onscroll = orig), 1);
        return p;
    }
    p.onscroll = orig;
    if (hasFixedPos(p)) {
        return null;
    }
    return findScrollParent(p);
}
export function findScrollParentAll(el) {
    let l = el;
    const arr = [];
    while (1) {
        l = findScrollParent(l);
        if (l) {
            arr.push(l);
            if (hasFixedPos(l)) {
                break;
            }
        }
        else
            break;
    }
    return arr.length ? arr : null;
}