重要更新01/2015 - 不推荐使用mousewheel事件：

与此同时 mousewheel 事件已被弃用，并替换为 wheel 。

mousewheel ：//developer.mozilla.org/en-US/docs/Web/Events/mousewheel#wikiArticlerel =nofollow noreferrer> MDN文档：

MDN Docs for mousewheel say:

不要使用此轮事件。

Do not use this wheel event.

此接口是非标准的并且已弃用。它仅用于非Gecko浏览器。而是使用标准的***事件。

This interface is non-standard and deprecated. It was used in non-Gecko browsers only. Instead use the standard wheel event.

现在你应该使用类似的东西：

// This function checks if the specified event is supported by the browser.
// Source: http://perfectionkills.com/detecting-event-support-without-browser-sniffing/
function isEventSupported(eventName) {
    var el = document.createElement('div');
    eventName = 'on' + eventName;
    var isSupported = (eventName in el);
    if (!isSupported) {
        el.setAttribute(eventName, 'return;');
        isSupported = typeof el[eventName] == 'function';
    }
    el = null;
    return isSupported;
}

$(document).ready(function() {
    // Check which wheel event is supported. Don't use both as it would fire each event 
    // in browsers where both events are supported.
    var wheelEvent = isEventSupported('mousewheel') ? 'mousewheel' : 'wheel';

    // Now bind the event to the desired element
    $('#foo').on(wheelEvent, function(e) {
        var oEvent = e.originalEvent,
            delta  = oEvent.deltaY || oEvent.wheelDelta;

        // deltaY for wheel event
        // wheelData for mousewheel event

        if (delta > 0) {
            // Scrolled up
        } else {
            // Scrolled down
        }
    });
});

PS

对于评论来自康奈尔沃特金斯 - 你能用120解释除法吗？，

有一些关于 MSDN ：

onmousewheel事件是暴露wheelDelta属性的唯一事件。此属性指示车轮按钮旋转的距离，以120的倍数表示。正值表示车轮按钮已旋转远离用户。负值表示滚轮按钮已朝向用户旋转。

The onmousewheel event is the only event that exposes the wheelDelta property. This property indicates the distance that the wheel button has rotated, expressed in multiples of 120. A positive value indicates that the wheel button has rotated away from the user. A negative value indicates that the wheel button has rotated toward the user.

我遗漏了 delta / 120 参与我的方法，因为IMO没有任何好处。向上滚动 delta> 0 和向下 delta< 0 。简单。

I left out the delta / 120 part in my method as there's no benefit IMO. Scrolling up is delta > 0 and down delta < 0. Simple.