JavaScript面向对象编程（9）快速构建继承关系之整合原型链

前面我们铺垫了很多细节，是为了让大家更加明晰prototype的使用细节；

现在可以将前面的知识整合起来，写一个函数用于快速构建基于原型链的继承关系了：

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1function extend(Child, Parent) {

2   var F = function(){};

3   F.prototype = Parent.prototype;

4   Child.prototype = new F();

5   Child.prototype.constructor = Child;

6   Child.uber = Parent.prototype;

7}

8

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1  使用起来也特别简单： 

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1function Shape(){}

2// augment prototype

3Shape.prototype.name = 'shape';

4Shape.prototype.toString = function(){

5   var result = [];

6   if (this.constructor.uber) {

7       result[result.length] = this.constructor.uber.toString();//super.toString()

8   }

9   result[result.length] = this.name;

10  return result.join(', ');

11};

12function TwoDShape(){}

13//先继承，再增强

14extend(TwoDShape,Shape);

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16TwoDShape.prototype.name = '2D shape';

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18function Triangle(side, height) {

19  this.side = side;

20  this.height = height;

21}

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23extend(Triangle,TwoDShape);

24Triangle.prototype.name = 'Triangle';

25//使用继承而来的toString方法

26alert(new Triangle(10,5).toString());

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