<script type="text/javascript">//继承第一种方式：对象冒充function Parent(username) //父类对象
{this.username = username; //下面的代码最关键的部分就是将子对象的this传递给了父对象this.sayHello = function(){alert(this.username);}
}function Child(username, password) //子类对象
{//下面三行代码是最关键的代码this.method = Parent; //定义method属性，指向Parent，即指向了上面的构造函数this.method(username);//把username传递过去，调用构造函数，此时Parent函数体中的this即当前的Child对象delete this.method; //删掉method属性，因为Child已经具备了Parent的属性和方法//下面可以增加一些子类特有的属性和方法this.password = password;this.sayWorld = function(){alert(this.password);}
}//生成这两个类的对象
var parent = new Parent("zhangsan");
var child = new Child("lisi", "1234");parent.sayHello();child.sayHello();
child.sayWorld();</script>

<script type="text/javascript">//call方法方式,Function对象中的方法function test(str, str2)
{alert(this.name + ", " + str + ", " + str2);
}var object = new Object();
object.name = "zhangsan";//test.call相当于调用了test函数
test.call(object, "shengsiyuan", "hello"); //将object赋给了this
//第一个参数赋给this，后面的参数逐次赋给方法参数</script>

<script type="text/javascript">//使用call方式实现对象的继承function Parent(username)
{this.username = username;this.sayHello = function(){alert(this.username);}
}function Child(username, password)
{Parent.call(this, username);//这样语句很关键，等价于对象冒充中的三行语句//执行之后子类就具有了基类的属性和方法//子对象的新增属性和方法this.password = password;this.sayWorld = function(){alert(this.password);}
}var parent = new Parent("zhangsan");var child = new Child("lisi", "123");parent.sayHello();child.sayHello();
child.sayWorld();</script>

<script type="text/javascript">//使用apply方法实现对象继承function Parent(username)
{this.username = username;this.sayHello = function(){alert(this.username);}
}function Child(username, password)
{Parent.apply(this, new Array(username));//apply方法方式实现继承，后面的参数以数组的形式传入this.password = password;this.sayWorld = function(){alert(this.password);}
}var parent = new Parent("zhangsan");
var child = new Child("lisi", "123");parent.sayHello();child.sayHello();
child.sayWorld();</script>

<script type="text/javascript">//使用原型链（prototype chain）方式实现对象继承function Parent()
{}Parent.prototype.hello = "hello";
Parent.prototype.sayHello = function()
{alert(this.hello);
}function Child()
{}Child.prototype = new Parent();//子类具有父类的属性和方法
//扩展属性
Child.prototype.world = "world";
Child.prototype.sayWorld = function()
{alert(this.world);
}var child = new Child();child.sayHello();
child.sayWorld();</script>

<script type="text/javascript">//使用混合方式实现对象继承(推荐)
//父对象
function Parent(hello)
{this.hello = hello;
}Parent.prototype.sayHello = function()
{alert(this.hello);
}
//子对象
function Child(hello, world)
{Parent.call(this, hello);//通过call实现属性的继承this.world = world;//新增加的属性
}Child.prototype = new Parent();//通过原型链实现方法的继承

Child.prototype.sayWorld = function()
{alert(this.world);
}var child = new Child("hello", "world");child.sayHello();
child.sayWorld();</script>

<script type="text/javascript">function Shape(edge)
{this.edge = edge;//属性，多少条边，通过构造函数的方式定义
}Shape.prototype.getArea = function()//通过原型的方式来定义方法
{return -1;//基类返回一个没有意义的值
}Shape.prototype.getEdge = function()
{return this.edge;
}//定义子对象Triangle
function Triangle(bottom, height)
{Shape.call(this, 3);//Triangle的属性this.bottom = bottom;this.height = height;
}Triangle.prototype = new Shape();//继承Shaple中的所有方法

Triangle.prototype.getArea = function()//重写方法
{return 0.5 * this.bottom * this.height;
}var triangle = new Triangle(10, 4);//alert(triangle.getEdge());
//alert(triangle.getArea());//另一个子类：四边形
function Rectangle(bottom, height)
{Shape.call(this, 4);this.bottom = bottom;this.height = height;
}Rectangle.prototype = new Shape();//通过原型继承父类的所有方法

Rectangle.prototype.getArea = function()//覆写方法
{return this.bottom * this.height;
}var rectangle = new Rectangle(20, 40);alert(rectangle.getEdge());
alert(rectangle.getArea());</script>