JavaScript 기생 조합 식 계승 분석

<script>
            //           
            function BaseClass(name,age){
                this.name=name;
                this.age=age;
            }
            
            //        sayName  
            BaseClass.prototype.sayName=function(){
                console.log(this.name);
            }
            
            //           
            function SubClass(name,age,job){
                //           ，       ，              。
                BaseClass.apply(this,arguments);
                
                //       
                this.job=job;
            }
            
            //                ，            
            inheritPrototype(SubClass,BaseClass);
            
            //       
            SubClass.prototype.sayJob=function(){
                console.log(this.job);
            }
            
            //       
            function inheritPrototype(subClass,baseClass){
                //           
                function fun(){};
                fun.prototype=baseClass.prototype;//             
                
                //                  ，              
                var obj=new fun();
                obj.constructor=SubClass
                SubClass.prototype=obj;
                
                /**
                 * backbone extend     
                 * 
                 * var Surrogate=function(){this.constructor=child;}
                 * Surrogate.prototype=parent.prototype;
                 * child.prototype=new Surrogate;
                 * 
                 */
            }
         
          var subClass=    new SubClass('  ',18,'Coder');
         
          console.log(subClass);
          subClass.sayName();
          subClass.sayJob();
        </script>