function SuperType(){
  this.colors = ["red", "blue", "green"];
}

function SubType(){
  //继承了 SuperType
  SuperType.apply(this);
}

var instance1 = new SubType();
instance1.colors.push("black");
alert(instance1.colors);  //red,blue,green,black

var instance2 = new SubType();
alert(instance2.colors);  //red,blue,green

function SuperType(name){
  this.name = name;
}

function SubType(){
  SuperType.call(this, "Bob");
  this.age = 18;
}

var instance1 = new SubType();
alert(instance1.age);  //18
alert(instance1.name);  //Bob

function SuperType(name){
  this.name = name;
  this.colors = ["red", "blue", "green"];
}
SuperType.prototype.sayName = function(){
  alert(this.name);
}

function SubType(name, age){
　　　　//继承属性
  SuperType.call(this, name);
  this.age = age;
}

　　//继承方法
SubType.prototype = new SuperType();
SubType.prototype.sayAge = function(){
  alert(this.age);
}

var instance1 = new SubType("Bob", 22);
instance1.colors.push("black");
alert(instance1.colors);   //red,blue,green,black
instance1.sayName();     //Bob
instance1.sayAge();     //22

var instance2 = new SubType("Alice", 21);
alert(instance2.colors);  //red,blue,green
instance2.sayName();    //Alice
instance2.sayAge();     //21