用js面向对象思想写类的例子

一个简单的题目：

写一个形状类，再写一个三角形类和一个矩形类，用面向对象的方式实现，输出各个形状的边数和面积。

三角形和矩形继承自形状类。

 

源码如下：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
</head>
<body>
    <script type="text/javascript">
       
        //-------------抽象类形状--------------
        function Shape(edges) {
            this.edges = edges;
        }

        //定义一个虚方法，用于重写

        Shape.prototype.getArea = function () {
            return -1;
        }

        Shape.prototype.getEdges = function () {
            return this.edges;
        }

        //--------------三角形----------------
        function Triangle(bottom, height) {
            Shape.call(this, 3);
            this.bottom = bottom;
            this.height = height;
        }

        //继承
        Triangle.prototype = new Shape();
        //重写方法
        Triangle.prototype.getArea = function () {
            return 0.5 * this.bottom * this.height;
        }

        //---------------矩形----------------
        function Rectangle(bottom, height) {
            Shape.call(this, 4);
            this.bottom = bottom;
            this.height = height;
        }
        //继承
        Rectangle.prototype = new Shape();
        //重写方法
        Rectangle.prototype.getArea = function () {
            return this.bottom * this.height;
        }


        //-------------测试-------------------
        var tri = new Triangle(4, 5);

        document.write(tri.getEdges() + "<br>");
        document.write(tri.getArea() + "<br>");

        var rect = new Rectangle(20, 40);
        document.write(rect.getEdges() + "<br>");
        document.write(rect.getArea() + "<br>");
    </script>
</body>
</html>

posted @ 2011-03-27 14:30  山之松  阅读(2293)  评论(0)    收藏  举报