如何实现C类？

Question

var A = function(name){

  this.name=name;

}

A.prototype = {

  sayName:function(){

    alert(this.name);

  }

}

var B = function(age){

  this.age = age;

}

B.prototype = {

  sayAge : function(){

    alert(this.age)

  } 

}

//function C(){};

var c = new C("white",25);

c.sayName();

c.sayAge();