Get element from mouse position

gistfile1.js

var x,y;

document.onmousemove = function(e){
    e = e || window.event;
    x = e.clientX;
    y = e.clientY;
};

function elementAtMousePosition() {
    return document.elementFromPoint(x,y);
}

I have been struggling to figure out how to make elementFromPoint work. I am implementing a drag & drop using hammer.js and I would like to know when the panend event has fired which is the DOM element beneath the target

http://plnkr.co/edit/jSsELjc4XOKEk1ffq5Qh?p=preview