安德烈(Andrey)的提示，指出应该使用鼠标滚轮事件而不是滚动事件.

Hat tip to Andrey for pointing out that you should use the mousewheel event rather than the scroll event.

<div class="container" data-bind="foreach: items, event: { mousewheel: scrolled }">

在mousewheel事件中，deltaY将为您提供滚动方向，您可以使用它来更改选择的项目:

From the mousewheel event, deltaY will give you the scroll direction, which you can use to change which item is selected:

scrolled: function (vm, event) {
    var direction = Math.sign(event.deltaY), // 1 is down, -1 is up
        maxIdx = vm.items().length - 1,
        selectedIdx = vm.items.indexOf(vm.selected()) + direction;
    if (selectedIdx >= 0 && selectedIdx <= maxIdx) {
        vm.selected(vm.items()[selectedIdx]);
    }
    // return false; // implied as long as you don't return true
}

http://jsfiddle.net/vjLqauq5/8/