1 // JavaScript Document 2 //创建三个构造函数 3 function Shape(){ 4 this.name='ahape'; 5 this.toString=function(){
   return this.name;} 6 } 7  8 function TwoDShape(){ 9 this.name=''2D shape;10 }    11 function Triangle(side,height){12 this.name='Triangel';13 this.side=side;14 this.height=height;15 this.getArea=function(){
   return this.side * this.height/2;}16 }    17 18 //实现继承19 TwoDShape.prototype=new Shape();20 Triangle.prototype=new TwoDShape();21 //实现继承关系后，重置原型的构造器属性22 TwoDShape.prototype.constructor=TwoDShape;23 Triangle.prototype.constructor=Triangle;24 //创建一个Triangle对象，并调用getArea方法25 var my=new Triangle(5,10);26 my.getArea();