【Prototype 1.4.0】源码解读----全文注释版

/*  Prototype JavaScript framework, version 1.4.0
*  (c) 2005 Sam Stephenson <sam@conio.net>
*
*  Prototype is freely distributable under the terms of an MIT-style license.
*  For details, see the Prototype web site: http://prototype.conio.net/ 
*  这是一个JavaScript的框架,致力于简化动态的Web开发，完全按照面对对象的思想
*  进行Javascript开发，添加了迭代器的概念增强Javascript的设计能力。
*  Prototype框架构思独特充满了技巧性的代码，方便易用的工具类！
*
/*--------------------------------------------------------------------------*/

/* 【Prototype】定义一个全局对象,提供一个全局的基本信息和工具 */
var Prototype = {
Version: '1.4.0', //可以作为版本检测用
//用于脚本检测的正则表达式，经常使用所以放在这里起到全局常量的作用
ScriptFragment: '(?:<script.*?>)((\n|\r|.)*?)(?:<\/script>)',

emptyFunction: function() {},//空函数
K: function(x) {return x}//K方法返回参数本身，在后面经常用到
}

/*========================================================================================*/

/*
*【Class】对象的作用只有一个就是提供了一个定义类的模式
* 仅含有create 一个方法，返回一个构造函数。
* 一般使用如下
*     var X = Class.create();  返回一个类型
* 要使用 X 类型，需继续用 new X()来获取一个实例 这与C# JAVA类似
* 返回的构造函数会执行名为 initialize 的方法， initialize 是 Ruby 对象的构造器方法名字。
* 此时initialize方法还没有定义，其后的代码中创建新类型时会建立相应的同名方法,可以看作是一个抽象方法。
* 从C#角度讲可以理解为用Class.create()创建一个继承Object基类的类。
*
*/

var Class = {
create: function() {
return function() {  //下面使用Apply方法传递参数是一个常用的技巧
this.initialize.apply(this, arguments);
}
}
}

/*========================================================================================*/

//Abstract是一个空对象，它的作用仅仅是作为一个抽象的命名空间，所有在该对象下定义的类都是抽象类
//从而从形式上与实体类分开
var Abstract = new Object();

/*
*Object是所有对象的基类，这个基类有两个静态方法
*/
//把Source的所有属性和方法传递给Destination，实现了继承的效果
Object.extend = function(destination, source) {
for (property in source) {
destination[property] = source[property];
}
return destination;
}
//观察Object的组成，需要参数中的object实现自己的inspect方法
Object.inspect = function(object) {
try {
if (object == undefined) return 'undefined';
if (object == null) return 'null';
return object.inspect ? object.inspect() : object.toString();
} catch (e) {
if (e instanceof RangeError) return '';
throw e;
}
}

/*========================================================================================*/

//【Function】是所有函数对象的基类，可以通过对它的扩展实现对所有函数对象添加功能
/* 这里在绑定的时候旧可以传递参数而不是调用的时候才指定参数，bind方法接收多个参数
将函数绑定到第一个参数指定的对象上，并返回该方法的调用句柄
*/
Function.prototype.bind = function() {
// $A()方法的作用是把参数专为数组
//数组的shift方法作用是删除数组的第一个元素
var __method = this, args = $A(arguments), object = args.shift();
return function() {
return __method.apply(object, args.concat($A(arguments)));
//这里的$A(arguments)是条用返回函数句柄时传递的参数，不是bind方法的参数
}
}
/**
* 和bind一样，不过这个方法一般用做html控件对象的事件处理。所以要传递event对象
* 好像是重载了_method方法
*/

Function.prototype.bindAsEventListener = function(object) {
var __method = this;
return function(event) {
return __method.call(object, event || window.event);
}
}

/*========================================================================================*/

//【Function】是所有数值类型的基类

Object.extend(Number.prototype, {
toColorPart: function() {           //RGB-》16进制颜色
var digits = this.toString(16);
if (this < 16) return '0' + digits;
return digits;
},

succ: function() { //数值加一 var a=1; var b=a.succ; 那么b=2
return this + 1;
},

times: function(iterator) {
//这里的参数iterator是一个迭代器作用就是循环调用指定次数的iterator函数
//$R(start,end,exclusive)是创建ObjectRnge对象的快捷方式
$R(0, this, true).each(iterator);
return this;
}
});

/*========================================================================================*/

//提供了一个方法these，要求参数是函数的句柄，可以有多个。作用就是返回第一个成功执行的函数的返回值
var Try = {
these: function() {
var returnValue;

for (var i = 0; i < arguments.length; i++) {
var lambda = arguments[i];
try {
returnValue = lambda();
break;
} catch (e) {}
}

return returnValue;
}
}

/*========================================================================================*/

//定时器类用来实现Window.setInterval的效果，在给定时间间隔执行某一个函数，增加了对重复执行的控制S
var PeriodicalExecuter = Class.create();
PeriodicalExecuter.prototype = {
initialize: function(callback, frequency) {
//构造函数指定回调函数和执行频率，单位是秒
this.callback = callback;
this.frequency = frequency;
this.currentlyExecuting = false;

this.registerCallback();
},

/* 开始调用定时器，无需显示调用，在构造函数中就实现了自动调用，这一下面的
this.onTimerEvent.bind(this)如果写成this.onTimerEvent则this指针就会指向widows对象即setInterval的默认对象
从而不能正确的引用到下面两个函数上，也就失去了对正在执行函数的控制
*/

registerCallback: function() {
setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
},
//下面的函数相当于是回调函数的一个代理， setInterval是到了指定的时间就会强制执行而这里
//加入了一个判断如果callback函数执行的时间超过了一个时间片，则阻止其被重复执行
onTimerEvent: function() {
if (!this.currentlyExecuting) {
try {
this.currentlyExecuting = true;
this.callback();
} finally {
this.currentlyExecuting = false;
}
}
}
}
/*使用举例：
function GetOnlineCount()
{//获得在线人数
}
new PeriodicalExecuter(GetOnlineCount,10)每10秒获取一次
*/

/*========================================================================================*/
/* 框架核心内容--------【基础工具类】
/*========================================================================================*/

/*document.getElementById(id)获取一个指定ID的结点,是这个方法的快捷方式和扩展
可以指定多个参数返回一个对象数组。参数也不一定是ID也可以是对象本身的引用，例如
$('id')等价于$($('id'))
*/
function $() {
var elements = new Array();

for (var i = 0; i < arguments.length; i++) {
var element = arguments[i];
if (typeof element == 'string')
element = document.getElementById(element);

if (arguments.length == 1)
return element;

elements.push(element);
}

return elements;
}

/*========================================================================================*/
//【String】类的扩展

//删除字符串中的HTML标记
Object.extend(String.prototype, {
stripTags: function() {
return this.replace(/<\/?[^>]+>/gi, '');
},
//删除字符串中的脚本块
stripScripts: function() {
return this.replace(new RegExp(Prototype.ScriptFragment, 'img'), '');
},
//提取字符串中的所有脚本块，作为数组返回，每一个脚本作为一个数组元素
extractScripts: function() {
var matchAll = new RegExp(Prototype.ScriptFragment, 'img');
var matchOne = new RegExp(Prototype.ScriptFragment, 'im');
return (this.match(matchAll) || []).map(function(scriptTag) {
return (scriptTag.match(matchOne) || ['', ''])[1];
});
},
//提取字符串中的脚本并执行
evalScripts: function() {
return this.extractScripts().map(eval);
},
//将字符串进行html编码例如"<" --》"<"
escapeHTML: function() {
var div = document.createElement('div');
var text = document.createTextNode(this);
div.appendChild(text);
return div.innerHTML;
},
//对字符串进行html解码例如"<"--》"<"
unescapeHTML: function() {
var div = document.createElement('div');
div.innerHTML = this.stripTags();
return div.childNodes[0] ? div.childNodes[0].nodeValue : '';
},
//将查询字符串格式的字符串转换为键值对数组
//例如var s="a=1&b=2&c=3"; var s2=s.toQueryParams(); s2为{a:1,b:2,c:3}
toQueryParams: function() {
var pairs = this.match(/^\??(.*)$/)[1].split('&');
return pairs.inject({}, function(params, pairString) {
var pair = pairString.split('=');
params[pair[0]] = pair[1];
return params;
});
},
//字符串转换为字符数组 "abc"-->['a','b','c']
toArray: function() {
return this.split('');
},
//连字符--》骆驼样式 'good-man'-->'goodMan'
camelize: function() {
var oStringList = this.split('-');
if (oStringList.length == 1) return oStringList[0];

var camelizedString = this.indexOf('-') == 0
? oStringList[0].charAt(0).toUpperCase() + oStringList[0].substring(1)
: oStringList[0];

for (var i = 1, len = oStringList.length; i < len; i++) {
var s = oStringList[i];
camelizedString += s.charAt(0).toUpperCase() + s.substring(1);
}

return camelizedString;
},
//得到字符串的组成结构
inspect: function() {
return "'" + this.replace('\\', '\\\\').replace("'", '\\\'') + "'";
}
});
//定义了一个等价的函数
String.prototype.parseQuery = String.prototype.toQueryParams;

/*========================================================================================*/

//【Enumerable】可枚举接口 是整个1.4.0框架的核心工具，所有实现此接口的类必须要实现_each(iterator)方法

var $break    = new Object(); //首先定义了两个异常对象，用于进行迭代计算的控制
var $continue = new Object();

var Enumerable = {
//用于对对象的每一个元素遍历执行iterator迭代器函数
each: function(iterator) {
var index = 0;                //可选参数表示元素在枚举对象的次序
try {
this._each(function(value) {//value是枚举元素的值
try {
iterator(value, index++);
} catch (e) {
if (e != $continue) throw e;
}
});
} catch (e) {
if (e != $break) throw e;
}
},
//判断是否所有的枚举元素都能使iterator返回true
all: function(iterator) {
var result = true;
this.each(function(value, index) {
result = result && !!(iterator || Prototype.K)(value, index);
if (!result) throw $break;
});
return result;
},
//判断是否有枚举元素能使iterator返回true，有一个就是True
any: function(iterator) {
var result = true;
this.each(function(value, index) {
if (result = !!(iterator || Prototype.K)(value, index))
throw $break;
});
return result;
},
//对所有的枚举元素执行iterator迭代器函数 结果作为一个数组返回
collect: function(iterator) {
var results = [];
this.each(function(value, index) {
results.push(iterator(value, index));
});
return results;
},
//第一个素能使iterator返回true的枚举元素的值，没有返回undefined
detect: function (iterator) {
var result;
this.each(function(value, index) {
if (iterator(value, index)) {
result = value;
throw $break;
}
});
return result;
},
//找到所有的能使iterator迭代器函数返回true的枚举元素 作为一个数组返回
findAll: function(iterator) {
var results = [];
this.each(function(value, index) {
if (iterator(value, index))
results.push(value);
});
return results;
},
//找到素有匹配pattern的枚举元素，结果作为数组返回，iterator可选，如果不指定旧返回素有匹配pattern的枚举元素
grep: function(pattern, iterator) {//正则模式 迭代器
var results = [];
this.each(function(value, index) {
var stringValue = value.toString();
if (stringValue.match(pattern))
results.push((iterator || Prototype.K)(value, index));
})
return results;
},
//判断枚举对象中是否含有参数Object指定的值
include: function(object) {
var found = false;
this.each(function(value) {
if (value == object) {
found = true;
throw $break;
}
});
return found;
},
//将memo作为iterator的第一个参数，枚举元素作为iterator的第二个参数，枚举元素的次序作为第三个
//参数每次迭代器的返回值将作为下一个iterator的memo参数，从而所有的迭代执行都通过memo联系起来了

inject: function(memo, iterator) {
this.each(function(value, index) {
memo = iterator(memo, value, index);
});
return memo;
},
//对所有的枚举元素执行method方法 后面是要传递的参数
invoke: function(method) {
var args = $A(arguments).slice(1);
return this.collect(function(value) {
return value[method].apply(value, args);
});
},
//返回的最大的迭代器执行结果
max: function(iterator) {
var result;
this.each(function(value, index) {
value = (iterator || Prototype.K)(value, index);
if (value >= (result || value))
result = value;
});
return result;
},
//反之
min: function(iterator) {
var result;
this.each(function(value, index) {
value = (iterator || Prototype.K)(value, index);
if (value <= (result || value))
result = value;
});
return result;
},
//返回两个数组一组能使iterator返回true 另一组返回false
partition: function(iterator) {
var trues = [], falses = [];
this.each(function(value, index) {
((iterator || Prototype.K)(value, index) ?
trues : falses).push(value);
});
return [trues, falses];
},
//获取所有枚举元素的property属性值作为数组的返回
pluck: function(property) {
var results = [];
this.each(function(value, index) {
results.push(value[property]);
});
return results;
},
//与findall相反
reject: function(iterator) {
var results = [];
this.each(function(value, index) {
if (!iterator(value, index))
results.push(value);
});
return results;
},
//根据iterator的结果排序 最小的在前面 作为数组返回
sortBy: function(iterator) {
return this.collect(function(value, index) {
return {value: value, criteria: iterator(value, index)};
}).sort(function(left, right) {
var a = left.criteria, b = right.criteria;
return a < b ? -1 : a > b ? 1 : 0;
}).pluck('value');
},
//枚举对象--》数组
toArray: function() {
return this.collect(Prototype.K);
},
//接收多个枚举对象参数，最后一个可以是迭代器用于阵列转换
zip: function() {
var iterator = Prototype.K, args = $A(arguments);
if (typeof args.last() == 'function')
iterator = args.pop();

var collections = [this].concat(args).map($A);
return this.map(function(value, index) {
iterator(value = collections.pluck(index));
return value;
});
},
//返回枚举对象的字符串描述
inspect: function() {
return '#<Enumerable:' + this.toArray().inspect() + '>';
}
}
//等价函数定义
Object.extend(Enumerable, {
map:     Enumerable.collect,
find:    Enumerable.detect,
select:  Enumerable.findAll,
member:  Enumerable.include,
entries: Enumerable.toArray
});

/*========================================================================================*/
//【Array】数组对象

//参数转换为数组，如果参数定义了toarray则直接调用，否则枚举获得数组
var $A = Array.from = function(iterable) {
if (!iterable) return [];
if (iterable.toArray) {
return iterable.toArray();
} else {
var results = [];
for (var i = 0; i < iterable.length; i++)
results.push(iterable[i]);
return results;
}
}
//数组对象继承了Enumerable接口
Object.extend(Array.prototype, Enumerable);

Array.prototype._reverse = Array.prototype.reverse;

Object.extend(Array.prototype, {
//实现了枚举接口方法，用于对数组内的元素执行迭代器
_each: function(iterator) {
for (var i = 0; i < this.length; i++)
iterator(this[i]);
},
//清空数组
clear: function() {
this.length = 0;
return this;
},
//取得第一个元素
first: function() {
return this[0];
},
//取得最后一个元素
last: function() {
return this[this.length - 1];
},
//删除数组元素中所有的null undefined值 作为新数组返回，原数组不受影响
compact: function() {
return this.select(function(value) {
return value != undefined || value != null;
});
},
//展开所有数组元素不再嵌套
flatten: function() {
return this.inject([], function(array, value) {
return array.concat(value.constructor == Array ?
value.flatten() : [value]);
});
},
//数组中删除指定的元素，返回删除后的结果，原数组不受影响
without: function() {
var values = $A(arguments);
return this.select(function(value) {
return !values.include(value);
});
},
//Value元素在数组中的索引值
indexOf: function(object) {
for (var i = 0; i < this.length; i++)
if (this[i] == object) return i;
return -1;
},
//反转数组
reverse: function(inline) {
return (inline !== false ? this : this.toArray())._reverse();
},
//删除数组中第一个元素并返回这个元素的值
shift: function() {
var result = this[0];
for (var i = 0; i < this.length - 1; i++)
this[i] = this[i + 1];
this.length--;
return result;
},
//得到数组的字符串描述例如arr=[1,2,3]-----> "[1,2,3]"
inspect: function() {
return '[' + this.map(Object.inspect).join(', ') + ']';
}
});

/*========================================================================================*/
//【Hash】哈希对象

var Hash = {
//实现枚举接口方法从而使Hash对象也是枚举对象
_each: function(iterator) {
for (key in this) {
var value = this[key];
if (typeof value == 'function') continue;

var pair = [key, value];
pair.key = key;
pair.value = value;
iterator(pair);
}
},
//所有键数组
keys: function() {
return this.pluck('key');
},
//所有值数组
values: function() {
return this.pluck('value');
},
//合并哈希表，键相同就覆盖调用者
merge: function(hash) {
return $H(hash).inject($H(this), function(mergedHash, pair) {
mergedHash[pair.key] = pair.value;
return mergedHash;
});
},
//键值对组成查询字符串的形式
toQueryString: function() {
return this.map(function(pair) {
return pair.map(encodeURIComponent).join('=');
}).join('&');
},
//获取Hash对象的字符串描述
inspect: function() {
return '#<Hash:{' + this.map(function(pair) {
return pair.map(Object.inspect).join(': ');
}).join(', ') + '}>';
}
}
/*哈希表不是类而是对象所以不能用new的方法创建，而是用$H()函数
这个方法吧一个对象转换为哈希对象，对象的属性名为key 值为value
可枚举！！
*/
function $H(object) {
var hash = Object.extend({}, object || {});
Object.extend(hash, Enumerable);
Object.extend(hash, Hash);
return hash;
}

/*========================================================================================*/
//【ObjectRange】用于进行指定次数的循环运算，同样继承于枚举接口并实现_each方法
//有了这个方法基本上Javascript里面就不用for循环了

ObjectRange = Class.create();
Object.extend(ObjectRange.prototype, Enumerable);
Object.extend(ObjectRange.prototype, {
//构造函数同事指定了3个参数的值
initialize: function(start, end, exclusive) {
this.start = start; //其实索引
this.end = end;//结束索引
this.exclusive = exclusive;//表示是否包含结束索引
},

_each: function(iterator) {
var value = this.start;
do {
iterator(value);
value = value.succ();
} while (this.include(value));
},
//重写枚举接口的include方法，判断改循环的索引是否包含参数value的指定的值
include: function(value) {
if (value < this.start)
return false;
if (this.exclusive)
return value < this.end;
return value <= this.end;
}
});
//使用$R()方法快速创建objectRange对象
var $R = function(start, end, exclusive) {
return new ObjectRange(start, end, exclusive);
}

/*========================================================================================*/
/* 【Ajax模块】
/*========================================================================================*/
//【ajax对象】

var Ajax = {//创建浏览器兼容的XMLHttpRequest对象
getTransport: function() {
return Try.these(
function() {return new ActiveXObject('Msxml2.XMLHTTP')},
function() {return new ActiveXObject('Microsoft.XMLHTTP')},
function() {return new XMLHttpRequest()}
) || false;
},
//当前激活的请求数目
activeRequestCount: 0
}
//【Ajax.Responders对象】
Ajax.Responders = {
responders: [],//表示所有响应处理代理

_each: function(iterator) {
this.responders._each(iterator);
},
//注册一个响应代理
register: function(responderToAdd) {
if (!this.include(responderToAdd))
this.responders.push(responderToAdd);
},
//删除一个响应代理
unregister: function(responderToRemove) {
this.responders = this.responders.without(responderToRemove);
},
//分发一个回调函数，让所有半酣callback回调函数事件标识符的响应代理都被调用
//传递三个参数最后一个可选表示Json对象
dispatch: function(callback, request, transport, json) {
this.each(function(responder) {
if (responder[callback] && typeof responder[callback] == 'function') {
try {
responder[callback].apply(responder, [request, transport, json]);
} catch (e) {}
}
});
}
};

Object.extend(Ajax.Responders, Enumerable);
//统计当前活动请求的数目
Ajax.Responders.register({
//开始创建了一个请求
onCreate: function() {
Ajax.activeRequestCount++;
},
//请求结束
onComplete: function() {
Ajax.activeRequestCount--;
}
});

//【Ajax.Base类】进行服务器通信的基类
Ajax.Base = function() {};
Ajax.Base.prototype = {
setOptions: function(options) {
this.options = {
method:       'post',
asynchronous: true,
parameters:   ''
}
Object.extend(this.options, options || {});
},

responseIsSuccess: function() {
return this.transport.status == undefined
|| this.transport.status == 0
|| (this.transport.status >= 200 && this.transport.status < 300);
},

responseIsFailure: function() {
return !this.responseIsSuccess();
}
}
//【Ajax.Request类】用于向服务器端发送请求，封装了XmlHttpRequest
Ajax.Request = Class.create();
Ajax.Request.Events =
['Uninitialized', 'Loading', 'Loaded', 'Interactive', 'Complete'];

Ajax.Request.prototype = Object.extend(new Ajax.Base(), {
initialize: function(url, options) {
this.transport = Ajax.getTransport();
this.setOptions(options);//使用基类方法设置
this.request(url);
},

//向指定url发送请求 一般不会显示调用
request: function(url) {
var parameters = this.options.parameters || '';
if (parameters.length > 0) parameters += '&_=';

try {
this.url = url;
if (this.options.method == 'get' && parameters.length > 0)
this.url += (this.url.match(/\?/) ? '&' : '?') + parameters;

Ajax.Responders.dispatch('onCreate', this, this.transport);

this.transport.open(this.options.method, this.url,
this.options.asynchronous);

if (this.options.asynchronous) {
this.transport.onreadystatechange = this.onStateChange.bind(this);
setTimeout((function() {this.respondToReadyState(1)}).bind(this), 10);
}

this.setRequestHeaders();

var body = this.options.postBody ? this.options.postBody : parameters;
this.transport.send(this.options.method == 'post' ? body : null);

} catch (e) {
this.dispatchException(e);
}
},
//设置请求的Http头 类内部使用 一般无需显示调用
setRequestHeaders: function() {
var requestHeaders =
['X-Requested-With', 'XMLHttpRequest',
'X-Prototype-Version', Prototype.Version];

if (this.options.method == 'post') {
requestHeaders.push('Content-type',
'application/x-www-form-urlencoded');

/* Force "Connection: close" for Mozilla browsers to work around
* a bug where XMLHttpReqeuest sends an incorrect Content-length
* header. See Mozilla Bugzilla #246651.
*/
if (this.transport.overrideMimeType)
requestHeaders.push('Connection', 'close');
}

if (this.options.requestHeaders)
requestHeaders.push.apply(requestHeaders, this.options.requestHeaders);

for (var i = 0; i < requestHeaders.length; i += 2)
this.transport.setRequestHeader(requestHeaders[i], requestHeaders[i+1]);
},
//检测XMLHttpRquest对象的onstatechange事件类内部使用 一般无需显示调用
onStateChange: function() {
var readyState = this.transport.readyState;
if (readyState != 1)
this.respondToReadyState(this.transport.readyState);
},
//获取指定的Http头的内容
header: function(name) {
try {
return this.transport.getResponseHeader(name);
} catch (e) {}
},
//如果服务器返回了Http头"X-JOSN"则将其作为js执行并返回执行结果
evalJSON: function() {
try {
return eval(this.header('X-JSON'));
} catch (e) {}
},
//将XMLHttpRequest返回的responseText作为JS语句执行并返回执行结果
evalResponse: function() {
try {
return eval(this.transport.responseText);
} catch (e) {
this.dispatchException(e);
}
},
//处理XMLHttpRequest的readystate属性根据成功或失败调用Options对象中相应的回调函数
//同时通知Ajax.Responders中注册的响应处理句柄
respondToReadyState: function(readyState) {
var event = Ajax.Request.Events[readyState];
var transport = this.transport, json = this.evalJSON();

if (event == 'Complete') {
try {
(this.options['on' + this.transport.status]
|| this.options['on' + (this.responseIsSuccess() ? 'Success' : 'Failure')]
|| Prototype.emptyFunction)(transport, json);
} catch (e) {
this.dispatchException(e);
}

if ((this.header('Content-type') || '').match(/^text\/javascript/i))
this.evalResponse();
}

try {
(this.options['on' + event] || Prototype.emptyFunction)(transport, json);
Ajax.Responders.dispatch('on' + event, this, transport, json);
} catch (e) {
this.dispatchException(e);
}

/* Avoid memory leak in MSIE: clean up the oncomplete event handler */
if (event == 'Complete')
this.transport.onreadystatechange = Prototype.emptyFunction;
},

dispatchException: function(exception) {
(this.options.onException || Prototype.emptyFunction)(this, exception);
Ajax.Responders.dispatch('onException', this, exception);
}
});

/*========================================================================================*/
//【Ajax.Updater类】用于将获取的内容填充到指定的容器中去
Ajax.Updater = Class.create();

Object.extend(Object.extend(Ajax.Updater.prototype, Ajax.Request.prototype), {
//重写了构造函数
initialize: function(container, url, options) {
this.containers = {
success: container.success ? $(container.success) : $(container),
failure: container.failure ? $(container.failure) :
(container.success ? null : $(container))
}

this.transport = Ajax.getTransport();
this.setOptions(options);//可以指定evalscripts属性和insertion属性

var onComplete = this.options.onComplete || Prototype.emptyFunction;
this.options.onComplete = (function(transport, object) {
this.updateContent();
onComplete(transport, object);
}).bind(this);

this.request(url);
},

updateContent: function() {
var receiver = this.responseIsSuccess() ?
this.containers.success : this.containers.failure;
var response = this.transport.responseText;

if (!this.options.evalScripts)
response = response.stripScripts();

if (receiver) {
if (this.options.insertion) {
new this.options.insertion(receiver, response);
} else {
Element.update(receiver, response);
}
}

if (this.responseIsSuccess()) {
if (this.onComplete)
setTimeout(this.onComplete.bind(this), 10);
}
}
});

/*========================================================================================*/
//【Ajax.PeriodicalUpdater类】用于定时执行服务器异步调用，功能与Updater相同只是有了定时功能

Ajax.PeriodicalUpdater = Class.create();
Ajax.PeriodicalUpdater.prototype = Object.extend(new Ajax.Base(), {
initialize: function(container, url, options) {
this.setOptions(options);
this.onComplete = this.options.onComplete;
//区别就在下面两个属性 频率 衰减参数 指数增长！只要有一次不同旧回复原有频率
this.frequency = (this.options.frequency || 2);
this.decay = (this.options.decay || 1);

this.updater = {};
this.container = container;
this.url = url;

this.start();
},

start: function() {
this.options.onComplete = this.updateComplete.bind(this);
this.onTimerEvent();
},

stop: function() {
this.updater.onComplete = undefined;
clearTimeout(this.timer);
(this.onComplete || Prototype.emptyFunction).apply(this, arguments);
},

updateComplete: function(request) {
if (this.options.decay) {
this.decay = (request.responseText == this.lastText ?
this.decay * this.options.decay : 1);

this.lastText = request.responseText;
}
this.timer = setTimeout(this.onTimerEvent.bind(this),
this.decay * this.frequency * 1000);
},

onTimerEvent: function() {
this.updater = new Ajax.Updater(this.container, this.url, this.options);
}
});

/*========================================================================================*/
/*【文档操作的封装】
/*========================================================================================*/

//返回了一个数组包含了所有符合条件的结点的引用
document.getElementsByClassName = function(className, parentElement) { //parentElement不指定就在全局查找
var children = ($(parentElement) || document.body).getElementsByTagName('*');
return $A(children).inject([], function(elements, child) {
if (child.className.match(new RegExp("(^|\\s)" + className + "(\\s|$)")))
elements.push(child);
return elements;
});
}

/*【Element对象】用于对文档结点做一些统一的操作

*/

if (!window.Element) {
var Element = new Object();
}

Object.extend(Element, {
visible: function(element) {
return $(element).style.display != 'none';
},
//指定结点可见性的切换
toggle: function() {
for (var i = 0; i < arguments.length; i++) {
var element = $(arguments[i]);
Element[Element.visible(element) ? 'hide' : 'show'](element);
}
},

hide: function() {
for (var i = 0; i < arguments.length; i++) {
var element = $(arguments[i]);
element.style.display = 'none';
}
},

show: function() {
for (var i = 0; i < arguments.length; i++) {
var element = $(arguments[i]);
element.style.display = '';
}
},

remove: function(element) {
element = $(element);
element.parentNode.removeChild(element);
},
//将html片段填充到element指定的结点中
update: function(element, html) {
$(element).innerHTML = html.stripScripts();
setTimeout(function() {html.evalScripts()}, 10);
},
//获得element的绝对高度
getHeight: function(element) {
element = $(element);
return element.offsetHeight;
},

classNames: function(element) {
return new Element.ClassNames(element);
},

hasClassName: function(element, className) {
if (!(element = $(element))) return;
return Element.classNames(element).include(className);
},

addClassName: function(element, className) {
if (!(element = $(element))) return;
return Element.classNames(element).add(className);
},

removeClassName: function(element, className) {
if (!(element = $(element))) return;
return Element.classNames(element).remove(className);
},

// removes whitespace-only text node children
cleanWhitespace: function(element) {
element = $(element);
for (var i = 0; i < element.childNodes.length; i++) {
var node = element.childNodes[i];
if (node.nodeType == 3 && !/\S/.test(node.nodeValue))
Element.remove(node);
}
},

empty: function(element) {
return $(element).innerHTML.match(/^\s*$/);
},
//将浏览器的滚动条滚动到指定的结点的位置
scrollTo: function(element) {
element = $(element);
var x = element.x ? element.x : element.offsetLeft,
y = element.y ? element.y : element.offsetTop;
window.scrollTo(x, y);
},
//得到element的结点的绝对样式
getStyle: function(element, style) {
element = $(element);
var value = element.style[style.camelize()];
if (!value) {
if (document.defaultView && document.defaultView.getComputedStyle) {
var css = document.defaultView.getComputedStyle(element, null);
value = css ? css.getPropertyValue(style) : null;
} else if (element.currentStyle) {
value = element.currentStyle[style.camelize()];
}
}

if (window.opera && ['left', 'top', 'right', 'bottom'].include(style))
if (Element.getStyle(element, 'position') == 'static') value = 'auto';

return value == 'auto' ? null : value;
},
//设置结点样式 var style={background-color:'black',color:'red'} Element.setStyle($('div1'),style)
setStyle: function(element, style) {
element = $(element);
for (name in style)
element.style[name.camelize()] = style[name];
},

//获得结点的宽度高度 该方法无论结点是否可见 都能获得其大小
getDimensions: function(element) {
element = $(element);
if (Element.getStyle(element, 'display') != 'none')
return {width: element.offsetWidth, height: element.offsetHeight};

// All *Width and *Height properties give 0 on elements with display none,
// so enable the element temporarily
var els = element.style;
var originalVisibility = els.visibility;
var originalPosition = els.position;
els.visibility = 'hidden';
els.position = 'absolute';
els.display = '';
var originalWidth = element.clientWidth;
var originalHeight = element.clientHeight;
els.display = 'none';
els.position = originalPosition;
els.visibility = originalVisibility;
return {width: originalWidth, height: originalHeight};
},
//相对定位
makePositioned: function(element) {
element = $(element);
var pos = Element.getStyle(element, 'position');
if (pos == 'static' || !pos) {
element._madePositioned = true;
element.style.position = 'relative';
// Opera returns the offset relative to the positioning context, when an
// element is position relative but top and left have not been defined
if (window.opera) {
element.style.top = 0;
element.style.left = 0;
}
}
},
//取消相对定位
undoPositioned: function(element) {
element = $(element);
if (element._madePositioned) {
element._madePositioned = undefined;
element.style.position =
element.style.top =
element.style.left =
element.style.bottom =
element.style.right = '';
}
},
//使结点隐藏超出的部分 overflow=relative
makeClipping: function(element) {
element = $(element);
if (element._overflow) return;
element._overflow = element.style.overflow;
if ((Element.getStyle(element, 'overflow') || 'visible') != 'hidden')
element.style.overflow = 'hidden';
},

undoClipping: function(element) {
element = $(element);
if (element._overflow) return;
element.style.overflow = element._overflow;
element._overflow = undefined;
}
});

/*========================================================================================*/
//Toggle对象是Element.toggle方法的一个快捷用法
var Toggle = new Object();
Toggle.display = Element.toggle;

/*========================================================================================*/
//【Insertion命名空间】包含了4个类把指定的html片段插入到指定的结点的相应位置上
Abstract.Insertion = function(adjacency) {
this.adjacency = adjacency;
}

Abstract.Insertion.prototype = {
initialize: function(element, content) {
this.element = $(element);
this.content = content.stripScripts();

if (this.adjacency && this.element.insertAdjacentHTML) {
try {
this.element.insertAdjacentHTML(this.adjacency, this.content);
} catch (e) {
if (this.element.tagName.toLowerCase() == 'tbody') {
this.insertContent(this.contentFromAnonymousTable());
} else {
throw e;
}
}
} else {
this.range = this.element.ownerDocument.createRange();
if (this.initializeRange) this.initializeRange();
this.insertContent([this.range.createContextualFragment(this.content)]);
}

setTimeout(function() {content.evalScripts()}, 10);
},

contentFromAnonymousTable: function() {
var div = document.createElement('div');
div.innerHTML = '<table><tbody>' + this.content + '</tbody></table>';
return $A(div.childNodes[0].childNodes[0].childNodes);
}
}

var Insertion = new Object();

Insertion.Before = Class.create();
Insertion.Before.prototype = Object.extend(new Abstract.Insertion('beforeBegin'), {
initializeRange: function() {
this.range.setStartBefore(this.element);
},

insertContent: function(fragments) {
fragments.each((function(fragment) {
this.element.parentNode.insertBefore(fragment, this.element);
}).bind(this));
}
});

Insertion.Top = Class.create();
Insertion.Top.prototype = Object.extend(new Abstract.Insertion('afterBegin'), {
initializeRange: function() {
this.range.selectNodeContents(this.element);
this.range.collapse(true);
},

insertContent: function(fragments) {
fragments.reverse(false).each((function(fragment) {
this.element.insertBefore(fragment, this.element.firstChild);
}).bind(this));
}
});

Insertion.Bottom = Class.create();
Insertion.Bottom.prototype = Object.extend(new Abstract.Insertion('beforeEnd'), {
initializeRange: function() {
this.range.selectNodeContents(this.element);
this.range.collapse(this.element);
},

insertContent: function(fragments) {
fragments.each((function(fragment) {
this.element.appendChild(fragment);
}).bind(this));
}
});

Insertion.After = Class.create();
Insertion.After.prototype = Object.extend(new Abstract.Insertion('afterEnd'), {
initializeRange: function() {
this.range.setStartAfter(this.element);
},

insertContent: function(fragments) {
fragments.each((function(fragment) {
this.element.parentNode.insertBefore(fragment,
this.element.nextSibling);
}).bind(this));
}
});

/*========================================================================================*/
//【Element.ClassNames】获得一个结点的所有的class名称组成的对象，实现了枚举接口

Element.ClassNames = Class.create();
Element.ClassNames.prototype = {
initialize: function(element) {
this.element = $(element);
},

_each: function(iterator) {
this.element.className.split(/\s+/).select(function(name) {
return name.length > 0;
})._each(iterator);
},

set: function(className) {
this.element.className = className;
},

add: function(classNameToAdd) {
if (this.include(classNameToAdd)) return;
this.set(this.toArray().concat(classNameToAdd).join(' '));
},

remove: function(classNameToRemove) {
if (!this.include(classNameToRemove)) return;
this.set(this.select(function(className) {
return className != classNameToRemove;
}).join(' '));
},

toString: function() {//获得所有class的字符串表示空格隔开
return this.toArray().join(' ');
}
}
//表单域对象工具类
Object.extend(Element.ClassNames.prototype, Enumerable);
var Field = {
clear: function() {
for (var i = 0; i < arguments.length; i++)
$(arguments[i]).value = '';
},

focus: function(element) {
$(element).focus();
},

present: function() {
for (var i = 0; i < arguments.length; i++)
if ($(arguments[i]).value == '') return false;
return true;
},
//选中表单域
select: function(element) {
$(element).select();
},
//focus + select
activate: function(element) {
element = $(element);
element.focus();
if (element.select)
element.select();
}
}

/*【Form】表单工具对象*/

var Form = {
//表单数据序列化
serialize: function(form) {
var elements = Form.getElements($(form));
var queryComponents = new Array();

for (var i = 0; i < elements.length; i++) {
var queryComponent = Form.Element.serialize(elements[i]);
if (queryComponent)
queryComponents.push(queryComponent);
}

return queryComponents.join('&');
},
//获取所有表单域按照标记名排列
getElements: function(form) {
form = $(form);
var elements = new Array();

for (tagName in Form.Element.Serializers) {
var tagElements = form.getElementsByTagName(tagName);
for (var j = 0; j < tagElements.length; j++)
elements.push(tagElements[j]);
}
return elements;
},
//有一个满足就返回
getInputs: function(form, typeName, name) {
form = $(form);
var inputs = form.getElementsByTagName('input');

if (!typeName && !name)
return inputs;

var matchingInputs = new Array();
for (var i = 0; i < inputs.length; i++) {
var input = inputs[i];
if ((typeName && input.type != typeName) ||
(name && input.name != name))
continue;
matchingInputs.push(input);
}

return matchingInputs;
},
//整个表单域禁用
disable: function(form) {
var elements = Form.getElements(form);
for (var i = 0; i < elements.length; i++) {
var element = elements[i];
element.blur();
element.disabled = 'true';
}
},
//启用
enable: function(form) {
var elements = Form.getElements(form);
for (var i = 0; i < elements.length; i++) {
var element = elements[i];
element.disabled = '';
}
},
//获取第一个可用的表单域
findFirstElement: function(form) {
return Form.getElements(form).find(function(element) {
return element.type != 'hidden' && !element.disabled &&
['input', 'select', 'textarea'].include(element.tagName.toLowerCase());
});
},
//激活第一个表单域
focusFirstElement: function(form) {
Field.activate(Form.findFirstElement(form));
},

reset: function(form) {
$(form).reset();
}
}

//【Form.Element】 对特定的表单域进行操作
Form.Element = {
//序列化形成"&name=value"
serialize: function(element) {
element = $(element);
var method = element.tagName.toLowerCase();
var parameter = Form.Element.Serializers[method](element);

if (parameter) {
var key = encodeURIComponent(parameter[0]);
if (key.length == 0) return;

if (parameter[1].constructor != Array)
parameter[1] = [parameter[1]];

return parameter[1].map(function(value) {
return key + '=' + encodeURIComponent(value);
}).join('&');
}
},
//获得指定表单域的值
getValue: function(element) {
element = $(element);
var method = element.tagName.toLowerCase();
var parameter = Form.Element.Serializers[method](element);

if (parameter)
return parameter[1];
}
}
//【Form.Element.Serializers】针对不同的表单域进行序列化
Form.Element.Serializers = {
//一般用所有的<input>标记的序列化都可以
input: function(element) {
switch (element.type.toLowerCase()) {
case 'submit':
case 'hidden':
case 'password':
case 'text':
return Form.Element.Serializers.textarea(element);
case 'checkbox':
case 'radio':
return Form.Element.Serializers.inputSelector(element);
}
return false;
},

inputSelector: function(element) {
if (element.checked)
return [element.name, element.value];
},

textarea: function(element) {
return [element.name, element.value];
},

select: function(element) {
return Form.Element.Serializers[element.type == 'select-one' ?
'selectOne' : 'selectMany'](element);
},

selectOne: function(element) {
var value = '', opt, index = element.selectedIndex;
if (index >= 0) {
opt = element.options[index];
value = opt.value;
if (!value && !('value' in opt))
value = opt.text;
}
return [element.name, value];
},

selectMany: function(element) {
var value = new Array();
for (var i = 0; i < element.length; i++) {
var opt = element.options[i];
if (opt.selected) {
var optValue = opt.value;
if (!optValue && !('value' in opt))
optValue = opt.text;
value.push(optValue);
}
}
return [element.name, value];
}
}

//【获得表单域的值】
var $F = Form.Element.getValue;

/*========================================================================================*/
/*【Observer模式框架】 观察对象仅仅针对表单和表单域*/
/*========================================================================================*/

Abstract.TimedObserver = function() {}//定义了基于定时器的观察模式基类后面的类都继承了这个类
Abstract.TimedObserver.prototype = {
initialize: function(element, frequency, callback) {
this.frequency = frequency;//观察频率
this.element   = $(element);//被观察的对象
this.callback  = callback;//回调函数接受参数 被观察对象自身和触发事件时的值

this.lastValue = this.getValue();//这是观察的值！！
this.registerCallback();
},
//注册回调函数
registerCallback: function() {
setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
},
//每一个时间片触发一次该事件
onTimerEvent: function() {
var value = this.getValue();
if (this.lastValue != value) {
this.callback(this.element, value);
this.lastValue = value;
}
}
}

//【Form.Element.Observer类】实现了getvalue方法
Form.Element.Observer = Class.create();
Form.Element.Observer.prototype = Object.extend(new Abstract.TimedObserver(), {
getValue: function() {
return Form.Element.getValue(this.element);
}
});

//【Form.Observer类】实现了getvalue方法，只要有一个表单域发生变化就会触发回调
Form.Observer = Class.create();
Form.Observer.prototype = Object.extend(new Abstract.TimedObserver(), {
getValue: function() {
return Form.serialize(this.element);
}
});

//【Abstract.EventObserver 类】基于事件的Oberver模式的基类 后面的具体类都继承这个类

Abstract.EventObserver = function() {}
Abstract.EventObserver.prototype = {
initialize: function(element, callback) {
this.element  = $(element);
this.callback = callback;

this.lastValue = this.getValue();
if (this.element.tagName.toLowerCase() == 'form')
this.registerFormCallbacks();
else
this.registerCallback(this.element);
},
//每次发生事件时被调用 内部调用 无需显示调用
onElementEvent: function() {
var value = this.getValue();
if (this.lastValue != value) {
this.callback(this.element, value);
this.lastValue = value;
}
},
//注册表表单域事件
registerFormCallbacks: function() {
var elements = Form.getElements(this.element);
for (var i = 0; i < elements.length; i++)
this.registerCallback(elements[i]);
},

registerCallback: function(element) {
if (element.type) {
switch (element.type.toLowerCase()) {
case 'checkbox':
case 'radio':
Event.observe(element, 'click', this.onElementEvent.bind(this));
break;
case 'password':
case 'text':
case 'textarea':
case 'select-one':
case 'select-multiple':
Event.observe(element, 'change', this.onElementEvent.bind(this));
break;
}
}
}
}
//【Form.Element.EventObserver】
Form.Element.EventObserver = Class.create();
Form.Element.EventObserver.prototype = Object.extend(new Abstract.EventObserver(), {
getValue: function() {
return Form.Element.getValue(this.element);
}
});
//【Form.EventObserver】
Form.EventObserver = Class.create();
Form.EventObserver.prototype = Object.extend(new Abstract.EventObserver(), {
getValue: function() {
return Form.serialize(this.element);
}
});

/*========================================================================================*/
/*【事件处理:对Event对象的扩展】对javascript事件处理机制进行封装*/
/*========================================================================================*/
if (!window.Event) {
var Event = new Object();
}

Object.extend(Event, {
KEY_BACKSPACE: 8,
KEY_TAB:       9,
KEY_RETURN:   13,
KEY_ESC:      27,
KEY_LEFT:     37,
KEY_UP:       38,
KEY_RIGHT:    39,
KEY_DOWN:     40,
KEY_DELETE:   46,
//获取触发事件的对象
element: function(event) {
return event.target || event.srcElement;
},

isLeftClick: function(event) {
return (((event.which) && (event.which == 1)) ||
((event.button) && (event.button == 1)));
},

pointerX: function(event) {
return event.pageX || (event.clientX +
(document.documentElement.scrollLeft || document.body.scrollLeft));
},

pointerY: function(event) {
return event.pageY || (event.clientY +
(document.documentElement.scrollTop || document.body.scrollTop));
},
//停止事件的传递
stop: function(event) {
if (event.preventDefault) {
event.preventDefault();
event.stopPropagation();
} else {
event.returnValue = false;
event.cancelBubble = true;
}
},

// find the first node with the given tagName, starting from the
// node the event was triggered on; traverses the DOM upwards
findElement: function(event, tagName) {
var element = Event.element(event);
while (element.parentNode && (!element.tagName ||
(element.tagName.toUpperCase() != tagName.toUpperCase())))
element = element.parentNode;
return element;
},

observers: false,

_observeAndCache: function(element, name, observer, useCapture) {
if (!this.observers) this.observers = [];
if (element.addEventListener) {
this.observers.push([element, name, observer, useCapture]);
element.addEventListener(name, observer, useCapture);
} else if (element.attachEvent) {
this.observers.push([element, name, observer, useCapture]);
element.attachEvent('on' + name, observer);
}
},
//删除所有通过Event.observers绑定的事件
unloadCache: function() {
if (!Event.observers) return;
for (var i = 0; i < Event.observers.length; i++) {
Event.stopObserving.apply(this, Event.observers[i]);
Event.observers[i][0] = null;
}
Event.observers = false;
},
//绑定一个事件
observe: function(element, name, observer, useCapture) {
var element = $(element);
useCapture = useCapture || false;

if (name == 'keypress' &&
(navigator.appVersion.match(/Konqueror|Safari|KHTML/)
|| element.attachEvent))
name = 'keydown';

this._observeAndCache(element, name, observer, useCapture);
},
//取消事件绑定
stopObserving: function(element, name, observer, useCapture) {
var element = $(element);
useCapture = useCapture || false;

if (name == 'keypress' &&
(navigator.appVersion.match(/Konqueror|Safari|KHTML/)
|| element.detachEvent))
name = 'keydown';

if (element.removeEventListener) {
element.removeEventListener(name, observer, useCapture);
} else if (element.detachEvent) {
element.detachEvent('on' + name, observer);
}
}
});

//【结点的位置处理:Position对象】
/* prevent memory leaks in IE */
Event.observe(window, 'unload', Event.unloadCache, false);
var Position = {
// set to true if needed, warning: firefox performance problems
// NOT neeeded for page scrolling, only if draggable contained in
// scrollable elements
includeScrollOffsets: false,

// must be called before calling withinIncludingScrolloffset, every time the
// page is scrolled用于计算滚动条的位置信息
prepare: function() {
this.deltaX =  window.pageXOffset
|| document.documentElement.scrollLeft
|| document.body.scrollLeft
|| 0;
this.deltaY =  window.pageYOffset
|| document.documentElement.scrollTop
|| document.body.scrollTop
|| 0;
},
//计算节点的绝对滚动位置返回包含两个元素的数组到文档左侧 顶部的距离
realOffset: function(element) {
var valueT = 0, valueL = 0;
do {
valueT += element.scrollTop  || 0;
valueL += element.scrollLeft || 0;
element = element.parentNode;
} while (element);
return [valueL, valueT];
},
//计算结点相对于文档的绝对滚动位置，返回包含两个元素的数组到文档左侧 顶部的距离
cumulativeOffset: function(element) {
var valueT = 0, valueL = 0;
do {
valueT += element.offsetTop  || 0;
valueL += element.offsetLeft || 0;
element = element.offsetParent;
} while (element);
return [valueL, valueT];
},
//相对位置
positionedOffset: function(element) {
var valueT = 0, valueL = 0;
do {
valueT += element.offsetTop  || 0;
valueL += element.offsetLeft || 0;
element = element.offsetParent;
if (element) {
p = Element.getStyle(element, 'position');
if (p == 'relative' || p == 'absolute') break;
}
} while (element);
return [valueL, valueT];
},

offsetParent: function(element) {
if (element.offsetParent) return element.offsetParent;
if (element == document.body) return element;

while ((element = element.parentNode) && element != document.body)
if (Element.getStyle(element, 'position') != 'static')
return element;

return document.body;
},

// caches x/y coordinate pair to use with overlap是否在element内
within: function(element, x, y) {
if (this.includeScrollOffsets)
return this.withinIncludingScrolloffsets(element, x, y);
this.xcomp = x;
this.ycomp = y;
this.offset = this.cumulativeOffset(element);

return (y >= this.offset[1] &&
y <  this.offset[1] + element.offsetHeight &&
x >= this.offset[0] &&
x <  this.offset[0] + element.offsetWidth);
},

withinIncludingScrolloffsets: function(element, x, y) {
var offsetcache = this.realOffset(element);

this.xcomp = x + offsetcache[0] - this.deltaX;
this.ycomp = y + offsetcache[1] - this.deltaY;
this.offset = this.cumulativeOffset(element);

return (this.ycomp >= this.offset[1] &&
this.ycomp <  this.offset[1] + element.offsetHeight &&
this.xcomp >= this.offset[0] &&
this.xcomp <  this.offset[0] + element.offsetWidth);
},

// within must be called directly before
overlap: function(mode, element) {
if (!mode) return 0;
if (mode == 'vertical')
return ((this.offset[1] + element.offsetHeight) - this.ycomp) /
element.offsetHeight;
if (mode == 'horizontal')
return ((this.offset[0] + element.offsetWidth) - this.xcomp) /
element.offsetWidth;
},
//克隆结点 常用于拖放
clone: function(source, target) {
source = $(source);
target = $(target);
target.style.position = 'absolute';
var offsets = this.cumulativeOffset(source);
target.style.top    = offsets[1] + 'px';
target.style.left   = offsets[0] + 'px';
target.style.width  = source.offsetWidth + 'px';
target.style.height = source.offsetHeight + 'px';
},

page: function(forElement) {
var valueT = 0, valueL = 0;

var element = forElement;
do {
valueT += element.offsetTop  || 0;
valueL += element.offsetLeft || 0;

// Safari fix
if (element.offsetParent==document.body)
if (Element.getStyle(element,'position')=='absolute') break;

} while (element = element.offsetParent);

element = forElement;
do {
valueT -= element.scrollTop  || 0;
valueL -= element.scrollLeft || 0;
} while (element = element.parentNode);

return [valueL, valueT];
},

clone: function(source, target) {
var options = Object.extend({
setLeft:    true,
setTop:     true,
setWidth:   true,
setHeight:  true,
offsetTop:  0,
offsetLeft: 0
}, arguments[2] || {})

// find page position of source
source = $(source);
var p = Position.page(source);

// find coordinate system to use
target = $(target);
var delta = [0, 0];
var parent = null;
// delta [0,0] will do fine with position: fixed elements,
// position:absolute needs offsetParent deltas
if (Element.getStyle(target,'position') == 'absolute') {
parent = Position.offsetParent(target);
delta = Position.page(parent);
}

// correct by body offsets (fixes Safari)
if (parent == document.body) {
delta[0] -= document.body.offsetLeft;
delta[1] -= document.body.offsetTop;
}

// set position
if(options.setLeft)   target.style.left  = (p[0] - delta[0] + options.offsetLeft) + 'px';
if(options.setTop)    target.style.top   = (p[1] - delta[1] + options.offsetTop) + 'px';
if(options.setWidth)  target.style.width = source.offsetWidth + 'px';
if(options.setHeight) target.style.height = source.offsetHeight + 'px';
},
//绝对定位
absolutize: function(element) {
element = $(element);
if (element.style.position == 'absolute') return;
Position.prepare();

var offsets = Position.positionedOffset(element);
var top     = offsets[1];
var left    = offsets[0];
var width   = element.clientWidth;
var height  = element.clientHeight;

element._originalLeft   = left - parseFloat(element.style.left  || 0);
element._originalTop    = top  - parseFloat(element.style.top || 0);
element._originalWidth  = element.style.width;
element._originalHeight = element.style.height;

element.style.position = 'absolute';
element.style.top    = top + 'px';;
element.style.left   = left + 'px';;
element.style.width  = width + 'px';;
element.style.height = height + 'px';;
},
//相对定位
relativize: function(element) {
element = $(element);
if (element.style.position == 'relative') return;
Position.prepare();

element.style.position = 'relative';
var top  = parseFloat(element.style.top  || 0) - (element._originalTop || 0);
var left = parseFloat(element.style.left || 0) - (element._originalLeft || 0);

element.style.top    = top + 'px';
element.style.left   = left + 'px';
element.style.height = element._originalHeight;
element.style.width  = element._originalWidth;
}
}

// Safari returns margins on body which is incorrect if the child is absolutely
// positioned.  For performance reasons, redefine Position.cumulativeOffset for
// KHTML/WebKit only.
if (/Konqueror|Safari|KHTML/.test(navigator.userAgent)) {
Position.cumulativeOffset = function(element) {
var valueT = 0, valueL = 0;
do {
valueT += element.offsetTop  || 0;
valueL += element.offsetLeft || 0;
if (element.offsetParent == document.body)
if (Element.getStyle(element, 'position') == 'absolute') break;

element = element.offsetParent;
} while (element);

return [valueL, valueT];
}
}

//--------->完成