最优化: 圣杯模式

 function inherit( Target , Origin){
             function F();
             F.prototype = Origin.prototype;
             Target.prototype = new F();
             Target.prototype.constructor = Target;  //把Target的构造函数指向归位
             Target.prototype.uber= Origin.prototype; //为了让我们知道Target真正继承自谁
          }

 var inherit = (function(){
            var F =function (){} ;
            return function(Target,Origin){
                F.prototype = Origin.prototype;
                Target.prototype.constructor =  Target;
                Target.prototype.uber = Origin.prototype;
            }
        }())