Javascript继承的概念理解

function Animal(){this.head="头";this.foot="脚";this.name="动物";this.birthday=new Date();this.getAge=function(){return new Date()-this.birthday;}}function Bird(name){Animal.apply(this);//类似于Java的super(),父类如果有参数,则为super(args),即Animal.apply(this,args);this.name=name;}function Dog(name){Animal.call(this);//类似于Java的super(),父类如果有参数,则为super(args),即Animal.call(this,arg1,arg2,arg3);this.name=name;this.hand="手";}var bird=new Bird("鸟");bird.name;//鸟bird.hand;bird.getAge();var dog=new Dog("狗");dog.name;//狗dog.hand;dog.getAge();var animal = new Animal();animal.name;//动物