jquery mousewheel

(function($) {
    var toFix = ['wheel', 'mousewheel', 'DOMMouseScroll', 'MozMousePixelScroll'];
    var toBind = 'onwheel' in document || document.documentMode >= 9 ? ['wheel'] : ['mousewheel', 'DomMouseScroll', 'MozMousePixelScroll'];
    var lowestDelta, lowestDeltaXY;
    if ($.event.fixHooks) {
        for (var i = toFix.length; i;) {
            $.event.fixHooks[toFix[--i]] = $.event.mouseHooks
        }
    }
    $.event.special.mousewheel = {
        setup: function() {
            if (this.addEventListener) {
                for (var i = toBind.length; i;) {
                    this.addEventListener(toBind[--i], handler, false)
                }
            } else {
                this.onmousewheel = handler
            }
        },
        teardown: function() {
            if (this.removeEventListener) {
                for (var i = toBind.length; i;) {
                    this.removeEventListener(toBind[--i], handler, false)
                }
            } else {
                this.onmousewheel = null
            }
        }
    };
    $.fn.extend({
        mousewheel: function(fn) {
            return fn ? this.bind("mousewheel", fn) : this.trigger("mousewheel")
        },
        unmousewheel: function(fn) {
            return this.unbind("mousewheel", fn)
        }
    });
    function handler(event) {
        var orgEvent = event || window.event,
        args = [].slice.call(arguments, 1),
        delta = 0,
        deltaX = 0,
        deltaY = 0,
        absDelta = 0,
        absDeltaXY = 0,
        fn;
        event = $.event.fix(orgEvent);
        event.type = "mousewheel";
        if (orgEvent.wheelDelta) {
            delta = orgEvent.wheelDelta
        }
        if (orgEvent.detail) {
            delta = orgEvent.detail * -1
        }
        if (orgEvent.deltaY) {
            deltaY = orgEvent.deltaY * -1;
            delta = deltaY
        }
        if (orgEvent.deltaX) {
            deltaX = orgEvent.deltaX;
            delta = deltaX * -1
        }
        if (orgEvent.wheelDeltaY !== undefined) {
            deltaY = orgEvent.wheelDeltaY
        }
        if (orgEvent.wheelDeltaX !== undefined) {
            deltaX = orgEvent.wheelDeltaX * -1
        }
        absDelta = Math.abs(delta);
        if (!lowestDelta || absDelta < lowestDelta) {
            lowestDelta = absDelta
        }
        absDeltaXY = Math.max(Math.abs(deltaY), Math.abs(deltaX));
        if (!lowestDeltaXY || absDeltaXY < lowestDeltaXY) {
            lowestDeltaXY = absDeltaXY
        }
        fn = delta > 0 ? 'floor': 'ceil';
        delta = Math[fn](delta / lowestDelta);
        deltaX = Math[fn](deltaX / lowestDeltaXY);
        deltaY = Math[fn](deltaY / lowestDeltaXY);
        args.unshift(event, delta, deltaX, deltaY);
        return ($.event.dispatch || $.event.handle).apply(this, args)
    }
}));