【Prototype 1.4.0】源码解读(一)

/*  Prototype JavaScript framework, version 1.4.0
 *  (c) 2005 Sam Stephenson <[email protected]>
 *
 *  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);
    }
  }
});