Javascript中的继承机制6------xbObjects-优快云博客

本文通过实例演示了如何使用xbObjects库在JavaScript中实现类的定义、继承、方法重载及调用超类方法等功能。具体包括颜色类的创建与多边形类的继承扩展，如三角形和矩形面积的计算。

xbObjects下载地址：http://archive.bclary.com/xbProjects-docs/xbObject/

xbObjects不仅支持继承，还支持方法的重载和调用超类方法的能力。

代码如下：

重载多边形

<html> <head> <title>Example</title> <script type="text/javascript" src="xbObjects.js"></script> </head> <body> <script type="text/javascript"> _classes.registerClass("Polygon"); function Polygon(iSides) { _classes.defineClass("Polygon", prototypeFunction); this.init(iSides); function prototypeFunction() { Polygon.prototype.init = function(iSides) { this.parentMethod("init"); this.sides = iSides; }; Polygon.prototype.getArea = function () { return 0; }; } } _classes.registerClass("Triangle", "Polygon"); function Triangle(iBase, iHeight) { _classes.defineClass("Triangle", prototypeFunction); this.init(iBase,iHeight); function prototypeFunction() { Triangle.prototype.init = function(iBase, iHeight) { this.parentMethod("init", 3); this.base = iBase; this.height = iHeight; }; Triangle.prototype.getArea = function () { return 0.5 * this.base * this.height; }; } } _classes.registerClass("Rectangle", "Polygon"); function Rectangle(iLength, iWidth) { _classes.defineClass("Rectangle", prototypeFunction); this.init(iLength, iWidth); function prototypeFunction() { Rectangle.prototype.init = function(iLength, iWidth) { this.parentMethod("init", 4); this.length = iLength; this.width = iWidth; } Rectangle.prototype.getArea = function () { return this.length * this.width; }; } } var triangle = new Triangle(12, 4); var rectangle = new Rectangle(22, 10); alert(triangle.sides); alert(triangle.getArea()); alert(rectangle.sides); alert(rectangle.getArea()); </script> </body> </html>