prevent-body-scroll.js

canScrollElementVertically = (el, direction) => {
    if (direction > 0) {
        // Down
        return ((el.scrollTop + el.offsetHeight) < el.scrollHeight);
    } else {
        // Up
        return (el.scrollTop > 0);
    }
};


document.querySelector("vaadin-dialog-overlay").addEventListener("mousewheel", e => {
    let composed = e.composedPath();
    const bodyPosition = composed.indexOf(document.body);
    if (bodyPosition != -1) {
        composed = composed.slice(0, bodyPosition);
    }
    if (e.deltaY && !composed.find(el => canScrollElementVertically(el, e.deltaY)))
        e.preventDefault();
});