JavaScript继承方式

  
    

   
     
   
     function
   
      parent(){
 
   
     this
   
     .x
   
     =
   
     10
   
     ;
}

   
     function
   
      child(){
 
   
     var
   
      parentObj
   
     =
   
     new
   
      parent();
 
   
     for
   
     (
   
     var
   
      p 
   
     in
   
      parentObj)
   
     this
   
     [p]
   
     =
   
     parentObj[p];
}

   
     var
   
      childObj
   
     =
   
     new
   
      child();
alert(childObj.x);
  
    

 

  
    

   
     
   
     function
   
      parent(){
 
   
     this
   
     .x
   
     =
   
     10
   
     ;
}

   
     function
   
      child(){
 
   
     this
   
     .parent
   
     =
   
     parent;
 
   
     this
   
     .parent();
 
   
     delete
   
      
   
     this
   
     .parent;
}

   
     var
   
      childObj
   
     =
   
     new
   
      child();
alert(childObj.x);
  
    

 

  
    

   
     
   
     function
   
      parent(){
 
   
     this
   
     .x
   
     =
   
     10
   
     ;
}

   
     function
   
      child(){
 parent.call(
   
     this
   
     );
}

   
     var
   
      childObj
   
     =
   
     new
   
      child();
alert(childObj.x);
  
    

 

原型抄写

   
     

    
      
    
      function
    
       parent(){
}
parent.prototype.x
    
      =
    
      1
    
      ;


    
      function
    
       child(){
}

    
      for
    
      (
    
      var
    
       p 
    
      in
    
       parent.prototype)child.prototype[p]
    
      =
    
      parent.prototype[p];
child.prototype.y
    
      =
    
      2
    
      ;


    
      var
    
       childObj
    
      =
    
      new
    
       child();
alert(childObj.x);
   
     

 

  
    

   
     
   
     function
   
      parent(string){
 
   
     var
   
      child
   
     =
   
     new
   
      Function(
   
     "
   
     this.x=10;
   
     "
   
     +
   
     string);
 
   
     return
   
      child;
}

   
     var
   
      child
   
     =
   
     new
   
      parent(
   
     "
   
     this.y=20;
   
     "
   
     );


   
     var
   
      childObj
   
     =
   
     new
   
      child();
alert(childObj.y);
  
    

 

  
    

   
     
   
     function
   
      parent(){
 
   
     this
   
     .x
   
     =
   
     10
   
     ;
}

   
     function
   
      child(){
}
child.prototype
   
     =
   
     new
   
      parent();

   
     var
   
      childObj
   
     =
   
     new
   
      child();
alert(childObj.x);
  
    

 

  
    

   
     
   
     function
   
      parent(){
 
   
     this
   
     .x
   
     =
   
     10
   
     ;
}

   
     function
   
      child(){
 
   
     var
   
      ret
   
     =
   
     new
   
      parent();
 ret.y
   
     =
   
     20
   
     ;
 
   
     return
   
      ret;
}


   
     var
   
      childObj
   
     =
   
     new
   
      child();
alert(childObj.x);