gistfile1.js

var dragStartStream = element.asEventStream('mousedown');
var dragEndStream = $(window).asEventStream('mouseup');
var dragStream = dragStartStream.flatMap(function(e){
    $('.human,.product').css('z-index','1');
    element.css('z-index','99');
    return $(window).asEventStream('mousemove').map(function(event){
        event.startX = e.offsetX;
        event.startY = e.offsetY;
        return event;
    }).takeUntil(dragEndStream);
});
dragStream.onValue(function(e){
    element.css("left", e.pageX - e.startX);
    element.css("top", e.pageY - e.startY);
});