<script type="text/javascript">
  //声明一个函数demo
  function Demo()
  {
  }
  //实例函数demo
  var demo = new Demo();
  //声明一个函数Demo1
  function Demo1(name,age)
  {
    this.name = name;
    this.age = age;
  }
  //实例一个函数Demo1
  var demo1 = new Demo1('谭勇',21);
  //运行下面试试
  console.log(demo1.name);
  console.log(demo1.age);
  //Demo2
  function Demo2(name,age)
  {
    var that = this;
    this.name = name;
    this.age = age;
    function a()
    {
      return that.name;
    }
    function b()
    {
      return that.age;
    }
    this.getName = a;
    this.getAge = b;
  }
  //实例一个函数Demo1
  var demo2 = new Demo2('谭勇',21);
  //运行下面试试
  console.log(demo2.name);
  console.log(demo2.age);
</script>

<script type="text/javascript">
  function Demo(name,age)
  {
    this.name = name;
    this.age = age;
  }
  function Son()
  {
    this.text = 'test text';
  }
  Son.prototype = new Demo('谭勇',22);
  var __son = new Son();
  //试试
  console.log(__son.name);
  console.log(__son.age);
  console.log(__son.text);
  //组合继承
  function Son1()
  {
    this.text1 = 'my test son1';
  }
  Son1.prototype.Demo = new Demo('谭勇',22);
  Son1.prototype.Son1 = new Son1();
  var __son1 = new Son1();
  console.log(__son1.Demo.name);
  console.log(__son1.Demo.age);
  console.log(__son1.Son1.text);
  console.log(__son1.text1);
</script>