滚动条惯性滚动，页面平滑滚动

! function(a) {
        a(document).ready(function() {
            function q() {
                if(document.URL.indexOf("google.com/reader/view") > -1 && (g = !0), i)
                    for(var a = i.split(/[,
] ?/), b = a.length; b--;)
                        if(document.URL.indexOf(a[b]) > -1) {
                            D("mousewheel", v), g = !0;
                            break
                        }
            }

            function r() {
                if(document.body) {
                    var a = document.body,
                        b = document.documentElement,
                        c = window.innerHeight,
                        d = a.scrollHeight;
                    if(o = document.compatMode.indexOf("CSS") >= 0 ? b : a, n = a, q(), l = !0, top != self) j = !0;
                    else if(d > c && (a.offsetHeight <= c || b.offsetHeight <= c) && (o.style.height = "auto", o.offsetHeight <= c)) {
                        var e = document.createElement("div");
                        e.style.clear = "both", a.appendChild(e)
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                    if(document.URL.indexOf("mail.google.com") > -1) {
                        var f = document.createElement("style");
                        f.innerHTML = ".iu { visibility: hidden }", (document.getElementsByTagName("head")[0] || b).appendChild(f)
                    }
                    m || (a.style.backgroundAttachment = "scroll"), g && D("keydown", w)
                }
            }

            function u(c, e, f, g) {
                if(g || (g = 1e3), F(e, f), s.push({
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                        y: f,
                        lastX: 0 > e ? .99 : -.99,
                        lastY: 0 > f ? .99 : -.99,
                        start: +new Date
                    }), !t) {
                    var h = function() {
                        for(var i = +new Date, j = 0, k = 0, l = 0; l < s.length; l++) {
                            var m = s[l],
                                n = i - m.start,
                                o = n >= b,
                                p = o ? 1 : n / b;
                            d && (p = H(p));
                            var q = m.x * p - m.lastX >> 0,
                                r = m.y * p - m.lastY >> 0;
                            j += q, k += r, m.lastX += q, m.lastY += r, o && (s.splice(l, 1), l--)
                        }
                        if(e) {
                            var u = c.scrollLeft;
                            c.scrollLeft += j, j && c.scrollLeft === u && (e = 0)
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                        if(f) {
                            var v = c.scrollTop;
                            c.scrollTop += k, k && c.scrollTop === v && (f = 0)
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                        e || f || (s = []), s.length ? setTimeout(h, g / a + 1) : t = !1
                    };
                    setTimeout(h, 0), t = !0
                }
            }

            function v(a) {
                l || r();
                var b = a.target,
                    d = B(b);
                if(!d || a.defaultPrevented || E(n, "embed") || E(b, "embed") && /.pdf/i.test(b.src)) return !0;
                var e = a.wheelDeltaX || 0,
                    f = a.wheelDeltaY || 0;
                e || f || (f = a.wheelDelta || 0), Math.abs(e) > 1.2 && (e *= c / 120), Math.abs(f) > 1.2 && (f *= c / 120), u(d, -e, -f), a.preventDefault()
            }

            function w(a) {
                var b = a.target,
                    c = a.ctrlKey || a.altKey || a.metaKey;
                if(/input|textarea|embed/i.test(b.nodeName) || b.isContentEditable || a.defaultPrevented || c) return !0;
                if(E(b, "button") && a.keyCode === p.spacebar) return !0;
                var d, e = 0,
                    f = 0,
                    g = B(n),
                    i = g.clientHeight;
                switch(g == document.body && (i = window.innerHeight), a.keyCode) {
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                        f = -h;
                        break;
                    case p.down:
                        f = h;
                        break;
                    case p.spacebar:
                        d = a.shiftKey ? 1 : -1, f = .9 * -d * i;
                        break;
                    case p.pageup:
                        f = .9 * -i;
                        break;
                    case p.pagedown:
                        f = .9 * i;
                        break;
                    case p.home:
                        f = -g.scrollTop;
                        break;
                    case p.end:
                        var j = g.scrollHeight - g.scrollTop - i;
                        f = j > 0 ? j + 10 : 0;
                        break;
                    case p.left:
                        e = -h;
                        break;
                    case p.right:
                        e = h;
                        break;
                    default:
                        return !0
                }
                u(g, e, f), a.preventDefault()
            }

            function x(a) {
                n = a.target
            }

            function A(a, b) {
                for(var c = a.length; c--;) y[z(a[c])] = b;
                return b
            }

            function B(a) {
                var b = [],
                    c = o.scrollHeight;
                do {
                    var d = y[z(a)];
                    if(d) return A(b, d);
                    if(b.push(a), c === a.scrollHeight) {
                        if(!j || o.clientHeight + 10 < c) return A(b, document.body)
                    } else if(a.clientHeight + 10 < a.scrollHeight && (overflow = getComputedStyle(a, "").getPropertyValue("overflow"), "scroll" === overflow || "auto" === overflow)) return A(b, a)
                } while (a = a.parentNode)
            }

            function C(a, b, c) {
                window.addEventListener(a, b, c || !1)
            }

            function D(a, b, c) {
                window.removeEventListener(a, b, c || !1)
            }

            function E(a, b) {
                return a.nodeName.toLowerCase() === b.toLowerCase()
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            function F(a, b) {
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            }

            function G(a) {
                var b, c, d;
                return a *= e, 1 > a ? b = a - (1 - Math.exp(-a)) : (c = Math.exp(-1), a -= 1, d = 1 - Math.exp(-a), b = c + d * (1 - c)), b * f
            }

            function H(a) {
                return a >= 1 ? 1 : 0 >= a ? 0 : (1 == f && (f /= G(1)), G(a))
            }
            var n, o, a = 150,
                b = 600,
                c = 150,
                d = !0,
                e = 5,
                f = 1,
                g = !1,
                h = 50,
                i = "",
                j = !1,
                k = {
                    x: 0,
                    y: 0
                },
                l = !1,
                m = !0,
                p = {
                    left: 37,
                    up: 38,
                    right: 39,
                    down: 40,
                    spacebar: 32,
                    pageup: 33,
                    pagedown: 34,
                    end: 35,
                    home: 36
                },
                s = [],
                t = !1,
                y = {};
            setInterval(function() {
                y = {}
            }, 1e4);
            var z = function() {
                var a = 0;
                return function(b) {
                    return b.uniqueID || (b.uniqueID = a++)
                }
            }();
            /chrome/.test(navigator.userAgent.toLowerCase()) && (C("mousedown", x), C("mousewheel", v), C("keydown", w), C("load", r))
        })
    }(jQuery);

直接引入即可