Prevent window scroll on scrollable element

preventWindowScroll.js

// Usage:
// var el = docuemnt.getElementById('scrollable-div');
// el.addEventListener('wheel', preventWindowScroll, false);
function preventWindowScroll(e) {
    var direction = e.deltaY < 0 ? 'up' : 'down';
    var el = e.currentTarget;
    var atTop = el.scrollTop <= 0;
    var atBottom = (el.scrollHeight - (el.clientHeight + el.scrollTop) <= 0);
    if ((direction === 'up' && atTop) || (direction === 'down' && atBottom)) {
        e.preventDefault();
        return false;
    }
}