function Person(name,sex,age){
   this.name = name;
   this.sex = sex;
   this.age = age;
}
Person.prototype.eat = function(){
   console.log("每个人都会吃饭");
}
function Programmer(name,sex,age){
   this.habby = "看书";
   Person.call(this,name,sex,age)
}
Programmer.prototype = Person.prototype;
Programmer.prototype.writeCode = function(){
   console.log("写代码");
}

var programmer = new Programmer("张三","男",20);
console.log(programmer);

面向对象组合继承