Create sticky elements within a container in vanilla javascript

sticky-within.js

function stickySharingIcons() {
    if (window.innerWidth > 768) {
        const stickyIcons = document.querySelectorAll(".sticky-sharing-icons");

        if (stickyIcons.length > 0) {
            for (var i = 0; i < stickyIcons.length; i++) {
                makeIconsSticky(stickyIcons[i], document.querySelector(".article-page-content"));
            }
        }   
    }
}

export function makeIconsSticky(stickyEl, target) {
    const initialLeftPost = stickyEl.style.left;
    const initPosLeft = stickyEl.getBoundingClientRect().left;

    document.addEventListener("scroll", () => {
        updateSticky(stickyEl, target, initialLeftPost, initPosLeft);
    });
}

export function updateSticky(el, target, leftStyle, leftAbs) {
    const articleVwTop = target.getBoundingClientRect().top;
    const stickyHeight = el.offsetHeight;

    if (articleVwTop < 0 && (articleVwTop * -1) <= (target.offsetHeight - stickyHeight)) {
        el.style.position = "fixed";
        el.style.left = leftAbs + "px";
        el.style.top = "0px";
    } else {
        el.style.position = "absolute";
        el.style.left = leftStyle;
        
        if (articleVwTop < 0 && articleVwTop <= (target.offsetHeight - el.offsetHeight)) {
            el.style.top = (target.offsetHeight - el.offsetHeight)
            + "px";
        }
    }
}

export default stickySharingIcons