window.addEventListener("keypress", function(e) {
    if(e.ctrlKey && !e.altKey && !e.shiftKey && !e.metaKey) {
        var up = e.keyCode == e.DOM_VK_UP;
        var down = e.keyCode == e.DOM_VK_DOWN;
        if(up || down) {
            if(up)
                alert("Ctrl+Up");
            else
                alert("Ctrl+Down");
            e.preventDefault();
            e.stopPropagation();
        }
    }
}, true);