基类方法

define(function(require,exports,module){
  
  function Class(o) {
    //把之前的函数转换 
    if (!(this instanceof Class) && isFunction(o)) {
        return classify(o)
      }  
  }

  Class.create=function(obj){
    function subClass(){
      if(this.constructor===subClass && this.initialize){
        this.initialize.apply(this,arguments);
      }
    }
    //真正创建
    implement.call(subClass,obj);

    //暴露静态方法
    return classify(subClass);
  }

  function classify(cls){
    //继承
    cls.extend=Class.extend;
    //扩展
    cls.implement=implement;
    return cls;
  }

  function implement(proto){
    var key, value;
    for(key in proto){
       value=proto[key];
       if(Class.Mutators.hasOwnProperty(key)){
        Class.Mutators[key].call(this, value)
       }else{
        this.prototype[key]=value;
       }
    }
  }

  Class.extend = function(properties) {
    properties || (properties = {})
    properties.Extends = this

    return Class.create(properties)
  }

  Class.Mutators={
    'Extends':function(parent){
      var existed = this.prototype;
      var proto = createProto(parent.prototype);
      mix(proto,existed);
      proto.constructor = this;

      this.prototype=proto;
      //经典
      this.superclass=parent.prototype; 
    },
    'Implements': function(items) {
      isArray(items) || (items = [items])
      var proto = this.prototype, item

      while (item = items.shift()) {
        mix(proto, item.prototype || item)
      }
    },
    'Statics': function(staticProperties) {
      mix(this, staticProperties)
    }
  }

 
  function Ctor() {
  }

  var createProto = Object.__proto__ ?
      function(proto) {
        return { __proto__: proto }
      } :
      function(proto) {
        Ctor.prototype = proto
        return new Ctor()
      }


  // Helpers
  // ------------

  function mix(r, s, wl) {
    // Copy "all" properties including inherited ones.
    for (var p in s) {
      if (s.hasOwnProperty(p)) {
        if (wl && indexOf(wl, p) === -1) continue

        // 在 iPhone 1 代等设备的 Safari 中，prototype 也会被枚举出来，需排除
        if (p !== 'prototype') {
          r[p] = s[p]
        }
      }
    }
  }

  var toString = Object.prototype.toString

  var isArray = Array.isArray || function(val) {
      return toString.call(val) === '[object Array]'
  }

  var isFunction = function(val) {
    return toString.call(val) === '[object Function]'
  }

  var indexOf = Array.prototype.indexOf ?
      function(arr, item) {
        return arr.indexOf(item)
      } :
      function(arr, item) {
        for (var i = 0, len = arr.length; i < len; i++) {
          if (arr[i] === item) {
            return i
          }
        }
        return -1
      }

  module.exports = Class
})

demo:

var Animal=Class.create({
    name:"动物",
    run:function(){
        console.log("我会跑步");
    }
})    

var Pig = Class.create({
    Extends:Animal,
    initialize: function(name) {
        console.log(Pig.superclass.name);
    },

    talk: function() {
        console.log('我是' + this.name);
    }
});

var a=new Pig("猪");

a.run();