[转载]Prototype之详细解说[转] - Sam Lin - 博客园

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[转载]Prototype之详细解说[转] – Sam Lin – 博客园.

/*  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.*?>)(( | |.)*?)(?:</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"<" --》"&lt"

  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"&lt"--》"<"

  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
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