滚轮

mouseWheel: function () {
    function mousewheel(obj, upfun, downfun) {
        if (document.attachEvent) {
            obj.attachEvent("onmousewheel", scrollFn)
        } else {
            if (document.addEventListener) {
                obj.addEventListener("mousewheel", scrollFn, false);
                obj.addEventListener("DOMMouseScroll", scrollFn, false)
            }
        }
    function scrollFn(e) {
        var ev = e || window.event;
        var dir = ev.wheelDelta || ev.detail;
        if (ev.preventDefault) {
            ev.preventDefault()
        } else {
            ev.returnValue = false
        }
        if (dir == -3 || dir == 120) {
            upfun()
        } else {
            downfun()
        }
    }
}

var that = this;
mousewheel($("." + that.bigimg)[0], function () {
    if ($("." + that.bigimg).innerWidth() > $("body").width() - 20) {
        return
    }
    if ($("." + that.bigimg).innerHeight() > $("body").height() - 50) {
        return
    }
    var zoomHeight = $("." + that.bigimg).innerHeight() * 1.03;
    var zoomWidth = $("." + that.bigimg).innerWidth() * 1.03;
    $("." + that.bigimg).css({height: zoomHeight + "px", width: zoomWidth + "px"})
}, function () {
    if ($("." + that.bigimg).innerWidth() < 100) {
        return
    }
    if ($("." + that.bigimg).innerHeight() < 100) {
        return
    }
    var zoomHeight = $("." + that.bigimg).innerHeight() / 1.03;
    var zoomWidth = $("." + that.bigimg).innerWidth() / 1.03;
    $("." + that.bigimg).css({height: zoomHeight + "px", width: zoomWidth + "px"})
})

}

(function () {
    var previousScroll = 0;
$(window).scroll(function(){
   var currentScroll = $(this).scrollTop();
   if (currentScroll > previousScroll){
       alert('down');
   } else {
      alert('up');
   }
   previousScroll = currentScroll;
});

}()); //run this anonymous function immediately