如何写一个通用的JavaScript效果库！(1/2)

/* 
    这个函数的代码来自 Prototype.js  http://prototype.conio.net/ 
    如果页面引用了prototype.js ,则可以删除下面这个函数, 
    当然,即使不删除也没关系,因为作了简单的兼容性判断 
*/ 
(function(){    
    if     (!("Prototype" in window)){ 
        Prototype={emptyFunction:function(){}}; 
        Class ={ 
            create: function(){return function(){this.initialize.apply(this, arguments)}} 
        };         
        $ = function(element){ 
            return typeof(element)=="string"?document.getElementById(element):element 
        }; 
        $A= function(arrLike){ 
            for(var i=0,ret=[];i<arrLike.length;i++) ret[i]=arrLike[i]; 
            return ret 
        };     

        Number.prototype.toColorPart =function(){return String("00"+this.toString(16)).slice(-2)};         
        Function.prototype.bind = function() { 
             var __method = this, args = $A(arguments), object = args.shift(); 
            return function(){return __method.apply(object, args.concat($A(arguments)))} 
        } 

        Position={  
             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]; 
            } 
        }         
    } 
})() 


/* 
    1.读取/设置 透明度, 
    2.如果只传了一个参数element,则返回 element的透明度 (0<value<1) 
    3.如果传了两个参数 element和value 则把element的透明度设置为value  value范围 0-1 
*/ 
function Opacity(element,value){ 
// by Go_Rush(阿舜) from http://ashun.cnblogs.com/ 
    var ret; 
    if (value===undefined){   //读取 
        if (!/msie/i.test(navigator.userAgent)) 
            if (ret=element.style.opacity) return parseFloat(ret);           
        try{return element.filters.item('alpha').opacity/100}catch(x){return 1.0} 
    }else{                   //设置         
        value=Math.min(Math.max(value,0.00001),0.999999)    //这句修复一些非ie浏览器opacity不能设置为1的bug 
        if (/msie/i.test(navigator.userAgent)) return element.style.filter="alpha(opacity="+value*100+")" 
        return element.style.opacity=value         
    } 
} 

 Effect          =Class.create(); 
 Effect.Fn     =new Object(); 
 Effect.Init   =new Object(); 
               //  By Go_Rush(阿舜) from http://ashun.cnblogs.com/ 
 Effect.prototype={ 
     initialize: function(element,options) { 
         this.element  = $(element); 
         this.options  = options || {}; 
         this.duration   = (this.options.duration || 2) * 1000;   //效果执行时间 
         this.fps            = this.options.fps || 40;                 //频率 
         //当前步长，注： 这个变量是递减的，当它0的时候意味着整个效果结束 
         this.steps        = Math.floor(this.duration/this.fps);    
         this.maxSteps = this.steps;             //整个效果的步长 
         this.setting     = new Object();   
         this.timer         = null;         

      if (this.options.delay){    // 延时处理 
                var _this=this; 
              setTimeout(function(){ 
                        _this.setup(_this); 
                        (_this.options.onStart || Prototype.emptyFunction)(_this); 
                        _this.run(); 
                 }, _this.options.delay*1000); 
         }else{ 
                  this.setup(this); 
                 (this.options.onStart || Prototype.emptyFunction)(this);         
                 this.run();       
         } 
    }, 
    run: function() { 
         if (this.isFinished())  return (this.options.onComplete || Prototype.emptyFunction)(this); 
         if (this.timer)   clearTimeout(this.timer); 
         this.duration -= this.fps; 
         this.steps--;                            
         var pos=1-this.steps/this.maxSteps    ;    //总进度的百分比 
         this.loop(this,pos);     
         (this.options.onUpdate || Prototype.emptyFunction)(this,pos);       
         this.timer = setTimeout(this.run.bind(this), this.fps); 
    }, 
    isFinished: function() {  
            return this.steps <= 0; 
    }, 
    setup:function(effect){       //初始化设置所有效果单元 
            for(var key in Effect.Init){ 
             if (typeof(Effect.Init[key])!="function") continue; 
             try{Effect.Init[key](this)}catch(x){} 
         } 
     }, 
    loop:function(effect,pos){           //执行所有效果单元 
         for(var key in Effect.Fn){ 
             if (typeof(Effect.Fn[key])!="function") continue; 
             try{Effect.Fn[key](effect,pos)}catch(x){} 
         } 
    } 
 } 

 if (effect.options.opacity===undefined) return; 
 effect.setting.opacity=Opacity(effect.element);  
} 

Effect.Fn.opacity=function(effect,pos){ 
 if (effect.options.opacity===undefined) return; 
 Opacity(effect.element,effect.setting.opacity+(effect.options.opacity-effect.setting.opacity)*pos);  
}