jq 滚轮监听事件

windowAddMouseWheel();
function windowAddMouseWheel() {
    var i = 0;
    var scrollFunc = function (e) {
        e = e || window.event;
        if (e.wheelDelta) {  //判断浏览器IE，谷歌滑轮事件
            if (e.wheelDelta > 0) { //当滑轮向上滚动时
                alert("滑轮向上滚动"+i);
            }
            if (e.wheelDelta < 0) { //当滑轮向下滚动时
                alert("滑轮向下滚动");
            }
        } else if (e.detail) {  //Firefox滑轮事件
            if (e.detail> 0) { //当滑轮向上滚动时
                i++;
                window.scrollTo(0,300*i);
                alert("滑轮向上滚动"+i);
            }
            if (e.detail< 0) { //当滑轮向下滚动时
                i--;
                window.scrollTo(0,300*i);
                alert("滑轮向下滚动"+i);
            }
        }
    };
    //给页面绑定滑轮滚动事件
    if (document.addEventListener) {
        document.addEventListener('DOMMouseScroll', scrollFunc, false);
    }
//滚动滑轮触发scrollFunc方法
    window.onmousewheel = document.onmousewheel = scrollFunc;
}