有关原型链的问题

Question

function Shape(){

    this.name='Shape';

    this.toString=function(){

        return this.name;

    };

}

function TwoDShape(){

    this.name='2D shape';

}

function Triangle(side,height){

    this.name='Triangle';

    this.side=side;

    this.height=height;

    this.getArea=function(){

        return this.side*this.height/2;

    };

}

TwoDShape.prototype=new Shape();

Triangle.prototype=new TwoDShape();

var my=new Triangle(5,10);

my.getArea();//25

my.toString();//"Triangle"

1.my.toString()被调用时，JavaScript引擎执行路径是怎样的？