How to stop window jumping when typing in autoresizing textarea

Question

I am using the accepted answer to this question to build a textarea that expands vertically as text overflows:

Answer 1

A way to do the accepted answer when the textarea is in a scrollable div:

function getScrollParent(node) {
    if (node == null) {
        return null;
    }

    if (node.scrollHeight > node.clientHeight) {
        return node;
    } else {
        return getScrollParent(node.parentNode);
    }
}

function resize(){
    // 'this' is the textarea
    const scrollParent = getScrollParent(this);
    const scrollTop = scrollParent ? scrollParent.scrollTop : null;
    const scrollLeft = scrollParent ? scrollParent.scrollLeft : null;

    this.style.height = "auto";
    this.style.height = this.scrollHeight + "px";

    if (scrollParent) {
        scrollParent.scrollTo(scrollLeft, scrollTop);
    }
};