非常好的一个JS代码（CJL.0.1.js）

/*!
     * Cloudgamer JavaScript Library v0.1
     * Copyright (c) 2009 cloudgamer
     * Blog: http://cloudgamer.cnblogs.com/
     * Date: 2009-10-15
     */

var $$, $$B, $$A, $$F, $$D, $$E, $$CE, $$S;
function wr(text, ap) {
    if (ap) {
        document.getElementById("WriteDiv").innerHTML += text;
    } else {
        document.getElementById("WriteDiv").innerHTML = text;
    }
}
(function (undefined) {

    var O, B, A, F, D, E, CE, S;

    /*Object*/

    O = function (id) {
        return "string" == typeof id ? document.getElementById(id) : id;
    };

    //保存了一个空的function，主要用来代替空function节省资源。
    O.emptyFunction = function () { };

    //扩展对象（override：是否继承属性值）destination格式：var a={name:'1',age:12'}或某个对象：new class();
    O.extend = function (destination, source, override) {
        if (override === undefined) override = true;
        for (var property in source) {
            if (override || !(property in destination)) {
                destination[property] = source[property];
            }
        }
        return destination;
    };

    //深度扩展，这里的深度跟深度复制里面的意思差不多，参考的是jQuery的extend。
    O.deepextend = function (destination, source) {
        for (var property in source) {
            var copy = source[property];
            if (destination === copy) continue;
            if (typeof copy === "object") {
                destination[property] = arguments.callee(destination[property] || {}, copy);
            } else {
                destination[property] = copy;
            }
        }
        return destination;
    };

    /*from youa*///就复杂一点，主要用来做继承，主要参考有啊的$extends（跟prototype的Class.create也类似）。
    O.wrapper = function (me, parent) {
        var ins = function () { me.apply(this, arguments); };
        var subclass = function () { };
        subclass.prototype = parent.prototype;
        ins.prototype = new subclass;
        return ins;
    };

    /*Browser*/

    /*from youa*/
    B = (function (ua) {
        var b = {
            msie: /msie/.test(ua) && !/opera/.test(ua),
            opera: /opera/.test(ua),
            safari: /webkit/.test(ua) && !/chrome/.test(ua),
            firefox: /firefox/.test(ua),
            chrome: /chrome/.test(ua)
        };
        var vMark = "";
        for (var i in b) {
            if (b[i]) { vMark = "safari" == i ? "version" : i; break; }
        }
        b.version = vMark && RegExp("(?:" + vMark + ")[\\/: ]([\\d.]+)").test(ua) ? RegExp.$1 : "0";

        b.ie = b.msie;
        b.ie6 = b.msie && parseInt(b.version, 10) == 6;
        b.ie7 = b.msie && parseInt(b.version, 10) == 7;
        b.ie8 = b.msie && parseInt(b.version, 10) == 8;

        return b;
    })(window.navigator.userAgent.toLowerCase());

    /*Array*/

    A = function () {

        var ret = {
            isArray: function (obj) {
                return Object.prototype.toString.call(obj) === "[object Array]";
            },
            indexOf: function (array, elt, from) {
                if (array.indexOf) {
                    return (from) ? array.indexOf(elt) : array.indexOf(elt, from);
                } else {
                    var len = array.length;
                    from = isNaN(from) ? 0
                        : from < 0 ? Math.ceil(from) + len : Math.floor(from);

                    for (; from < len; from++) { if (array[from] === elt) return from; }
                    return -1;
                }
            },
            lastIndexOf: function (array, elt, from) {
                if (array.lastIndexOf) {
                    return isNaN(from) ? array.lastIndexOf(elt) : array.lastIndexOf(elt, from);
                } else {
                    var len = array.length;
                    from = isNaN(from) || from >= len - 1 ? len - 1
                        : from < 0 ? Math.ceil(from) + len : Math.floor(from);

                    for (; from > -1; from--) { if (array[from] === elt) return from; }
                    return -1;
                }
            }
        };

        //定义一个基本的迭代函数eac
        //object：要迭代的对象，callback：回调函数：用于获取迭代对象的值（属性值属性名称，迭代对象，）
        function each(object, callback) {
            if (undefined === object.length) {
                for (var name in object) {
                    //  alert(name + ":" + object[name]);
                    if (false === callback(object[name], name, object)) break;
                }
            } else {
                for (var i = 0, len = object.length; i < len; i++) {
                    if (i in object) { if (false === callback(object[i], i, object)) break; }
                }
            }
        };

        //调用each方法
        each(
            //object参数
            {
                forEach: function (object, callback, thisp) {
                    each(object, function () { callback.apply(thisp, arguments); });
                },
                map: function (object, callback, thisp) {
                    var ret = [];
                    each(object, function () { ret.push(callback.apply(thisp, arguments)); });
                    return ret;
                },
                filter: function (object, callback, thisp) {
                    var ret = [];
                    each(object, function (item) {
                        callback.apply(thisp, arguments) && ret.push(item);
                    });
                    return ret;
                },
                every: function (object, callback, thisp) {
                    var ret = true;
                    each(object, function () {
                        if (!callback.apply(thisp, arguments)) { ret = false; return false; };
                    });
                    return ret;
                },
                some: function (object, callback, thisp) {
                    var ret = false;
                    each(object, function () {
                        if (callback.apply(thisp, arguments)) { ret = true; return false; };
                    });
                    return ret;
                }
            },
            //callback参数
        function (method, name) {
            ret[name] = function (object, callback, thisp) {
                if (object[name]) {
                    return object[name](callback, thisp);
                } else {
                    return method(object, callback, thisp);
                }
            }
        });

        return ret;
    }();

    /*Function*/

    F = (function () {
        var slice = Array.prototype.slice;
        return {
            bind: function (fun, thisp) {
                //将arguments转换成真正的数组
                var args = slice.call(arguments, 2);
                return function () {
                    return fun.apply(thisp, args.concat(slice.call(arguments)));//连起来
                }
            },
            bindAsEventListener: function (fun, thisp) {
                var args = slice.call(arguments, 2);
                return function (event) {
                    return fun.apply(thisp, [E.fixEvent(event)].concat(args));
                }
            }
        };
    })();

    /*Dom*/

    D = {
        getScrollTop: function (node) {
            var doc = node ? node.ownerDocument : document;
            return doc.documentElement.scrollTop || doc.body.scrollTop;
        },
        getScrollLeft: function (node) {
            var doc = node ? node.ownerDocument : document;
            return doc.documentElement.scrollLeft || doc.body.scrollLeft;
        },
        contains: document.defaultView
            ? function (a, b) { return !!(a.compareDocumentPosition(b) & 16); }
            : function (a, b) { return a != b && a.contains(b); },
        rect: function (node) {
            var left = 0, top = 0, right = 0, bottom = 0;
            //ie8的getBoundingClientRect获取不准确
            if (!node.getBoundingClientRect || B.ie8) {
                var n = node;
                while (n) { left += n.offsetLeft, top += n.offsetTop; n = n.offsetParent; };
                right = left + node.offsetWidth; bottom = top + node.offsetHeight;
            } else {
                var rect = node.getBoundingClientRect();
                left = right = D.getScrollLeft(node); top = bottom = D.getScrollTop(node);
                left += rect.left; right += rect.right;
                top += rect.top; bottom += rect.bottom;
            };
            return { "left": left, "top": top, "right": right, "bottom": bottom };
        },
        clientRect: function (node) {
            var rect = D.rect(node), sLeft = D.getScrollLeft(node), sTop = D.getScrollTop(node);
            rect.left -= sLeft; rect.right -= sLeft;
            rect.top -= sTop; rect.bottom -= sTop;
            return rect;
        },
        curStyle: document.defaultView
            ? function (elem) { return document.defaultView.getComputedStyle(elem, null); }
            : function (elem) { return elem.currentStyle; },
        getStyle: document.defaultView
            ? function (elem, name) {
                var style = document.defaultView.getComputedStyle(elem, null);
                return name in style ? style[name] : style.getPropertyValue(name);
            }
            : function (elem, name) {
                var style = elem.style, curStyle = elem.currentStyle;
                //透明度 from youa
                if (name == "opacity") {
                    if (/alpha\(opacity=(.*)\)/i.test(curStyle.filter)) {
                        var opacity = parseFloat(RegExp.$1);
                        return opacity ? opacity / 100 : 0;
                    }
                    return 1;
                }
                if (name == "float") { name = "styleFloat"; }
                var ret = curStyle[name] || curStyle[S.camelize(name)];
                //单位转换 from jqury
                if (!/^-?\d+(?:px)?$/i.test(ret) && /^\-?\d/.test(ret)) {
                    var left = style.left, rtStyle = elem.runtimeStyle, rsLeft = rtStyle.left;

                    rtStyle.left = curStyle.left;
                    style.left = ret || 0;
                    ret = style.pixelLeft + "px";

                    style.left = left;
                    rtStyle.left = rsLeft;
                }
                return ret;
            },
        setStyle: function (elems, style, value) {
            if (!elems.length) { elems = [elems]; }
            if (typeof style == "string") { var s = style; style = {}; style[s] = value; }
            A.forEach(elems, function (elem) {
                for (var name in style) {
                    var value = style[name];
                    if (name == "opacity" && B.ie) {
                        //ie透明度设置 from jquery
                        elem.style.filter = (elem.currentStyle && elem.currentStyle.filter || "").replace(/alpha\([^)]*\)/, "") + " alpha(opacity=" + (value * 100 | 0) + ")";
                    } else if (name == "float") {
                        elem.style[B.ie ? "styleFloat" : "cssFloat"] = value;
                    } else {
                        elem.style[S.camelize(name)] = value;
                    }
                };
            });
        },
        getSize: function (elem) {
            var width = elem.offsetWidth, height = elem.offsetHeight;
            if (!width && !height) {
                var repair = !D.contains(document.body, elem), parent;
                if (repair) {//如果元素不在body上
                    parent = elem.parentNode;
                    document.body.insertBefore(elem, document.body.childNodes[0]);
                }
                var style = elem.style,
                    cssShow = { position: "absolute", visibility: "hidden", display: "block", left: "-9999px", top: "-9999px" },
                    cssBack = { position: style.position, visibility: style.visibility, display: style.display, left: style.left, top: style.top };
                D.setStyle(elem, cssShow);
                width = elem.offsetWidth; height = elem.offsetHeight;
                D.setStyle(elem, cssBack);
                if (repair) {
                    parent ? parent.appendChild(elem) : document.body.removeChild(elem);
                }
            }
            return { "width": width, "height": height };
        }
    };

    /*Event*/
    E = (function () {
        /*from dean edwards*/
        var addEvent, removeEvent, guid = 1,
            storage = function (element, type, handler) {
                if (!handler.$$guid) handler.$$guid = guid++;
                if (!element.events) element.events = {};
                var handlers = element.events[type];
                if (!handlers) {
                    handlers = element.events[type] = {};
                    if (element["on" + type]) {
                        handlers[0] = element["on" + type];
                    }
                }
            };
        if (window.addEventListener) {
            var fix = { "mouseenter": "mouseover", "mouseleave": "mouseout" };
            addEvent = function (element, type, handler) {
                if (type in fix) {
                    storage(element, type, handler);
                    var fixhandler = element.events[type][handler.$$guid] = function (event) {
                        var related = event.relatedTarget;
                        if (!related || (element != related && !(element.compareDocumentPosition(related) & 16))) {
                            handler.call(this, event);
                        }
                    };
                    element.addEventListener(fix[type], fixhandler, false);
                } else {
                    element.addEventListener(type, handler, false);
                };
            };
            removeEvent = function (element, type, handler) {
                if (type in fix) {
                    if (element.events && element.events[type]) {
                        element.removeEventListener(fix[type], element.events[type][handler.$$guid], false);
                        delete element.events[type][handler.$$guid];
                    }
                } else {
                    element.removeEventListener(type, handler, false);
                };
            };
        } else {
            addEvent = function (element, type, handler) {
                storage(element, type, handler);
                element.events[type][handler.$$guid] = handler;
                element["on" + type] = handleEvent;
            };
            removeEvent = function (element, type, handler) {
                if (element.events && element.events[type]) {
                    delete element.events[type][handler.$$guid];
                }
            };
            function handleEvent() {
                var returnValue = true, event = fixEvent();
                var handlers = this.events[event.type];
                for (var i in handlers) {
                    this.$$handleEvent = handlers[i];
                    if (this.$$handleEvent(event) === false) {
                        returnValue = false;
                    }
                }
                return returnValue;
            };
        }

        function fixEvent(event) {
            if (event) return event;
            event = window.event;
            event.pageX = event.clientX + D.getScrollLeft(event.srcElement);
            event.pageY = event.clientY + D.getScrollTop(event.srcElement);
            event.target = event.srcElement;
            event.stopPropagation = stopPropagation;
            event.preventDefault = preventDefault;
            var relatedTarget = {
                "mouseout": event.toElement, "mouseover": event.fromElement
            }[event.type];
            if (relatedTarget) { event.relatedTarget = relatedTarget; }

            return event;
        };
        function stopPropagation() { this.cancelBubble = true; };
        function preventDefault() { this.returnValue = false; };

        return {
            "addEvent": addEvent,
            "removeEvent": removeEvent,
            "fixEvent": fixEvent
        };
    })();

    /*CustomEvent*/

    CE = (function () {
        var guid = 1;
        return {
            addEvent: function (object, type, handler) {
                if (!handler.$$$guid) handler.$$$guid = guid++;
                if (!object.cusevents) object.cusevents = {};
                if (!object.cusevents[type]) object.cusevents[type] = {};
                object.cusevents[type][handler.$$$guid] = handler;
            },
            removeEvent: function (object, type, handler) {
                if (object.cusevents && object.cusevents[type]) {
                    delete object.cusevents[type][handler.$$$guid];
                }
            },
            fireEvent: function (object, type) {
                if (!object.cusevents) return;
                var args = Array.prototype.slice.call(arguments, 2),
                    handlers = object.cusevents[type];
                for (var i in handlers) {
                    handlers[i].apply(object, args);
                }
            },
            clearEvent: function (object) {
                if (!object.cusevents) return;
                for (var type in object.cusevents) {
                    var handlers = object.cusevents[type];
                    for (var i in handlers) {
                        handlers[i] = null;
                    }
                    object.cusevents[type] = null;
                }
                object.cusevents = null;
            }
        };
    })();

    /*String*/

    S = {
        camelize: function (s) {
            return s.replace(/-([a-z])/ig, function (all, letter) { return letter.toUpperCase(); });
        }
    };

    /*System*/

    // remove css image flicker
    if (B.ie6) {
        try {
            document.execCommand("BackgroundImageCache", false, true);
        } catch (e) { }
    };

    /*define*/

    $$ = O; $$B = B; $$A = A; $$F = F; $$D = D; $$E = E; $$CE = CE; $$S = S;

})();

原文来自：

http://www.cnblogs.com/cloudgamer/archive/2009/10/29/Cloudgamer_JavaScript_Library.html

http://www.cnblogs.com/cloudgamer/archive/2009/08/10/FixedMenu.html