定义原型对象,继承对象.示例代码如下:

1. <html>

2. <head>

3.     <TITLE>原型_对象_继承TITLE>

4.     <SCRIPT Language = "JavaScript">

5.     {

6. 
   

7.         function Circle(x,y,r)

8.         {

9.             this.x=x;

10.             this.y=y;

11.             this.r=r;

12.         }

13.         Circle.prototype.pi = 3.1415926;

14.         function Circle_circumference()

15.         {

16.             return 2*this.pi*this.r;

17.         }

18. 
    

19.         Circle.prototype.circumference = Circle_circumference;

20.         var c= new Circle(0.0, 0.0, 5);

21.         var p = c.circumference();

22. 
    

23.         document.write("<br>c圆的周长为Circle(0.0, 0.0, 5):",p);

24. 
    

25.         document.write("<br>继承");

26.         function Circle_area()

27.         {

28.             return this.pi*this.r*this.r;

29.         }

30.         Circle.prototype.area = Circle_area;

31.         var mji = c.area();

32.         document.write("<br>c圆的面积为:",mji);

33. 
    

34. 
    

35.         document.write("<br><br>重定义:不继承Circle(0.0, 0.0, 10);");

36.         var C3 = new Circle(0.0, 0.0, 10);

37.         function area()

38.         {

39.             return 3*this.pi*this.r*this.r;

40.         }

41.         C3.area = area;

42.         p = C3.circumference();

43.         mji = C3.area();

44.         document.write("<br>C3圆的周长为:",p);

45.         document.write("<br>C3圆的面积为:",mji);

46.     }

47.     SCRIPT>

48. head>

49. html>