前面我们铺垫了非常多细节。是为了让大家更加明晰prototype的使用细节；

如今能够将前面的知识整合起来，写一个函数用于高速构建基于原型链的继承关系了：

function extend(Child, Parent) {
	var F = function(){};
	F.prototype = Parent.prototype;
	Child.prototype = new F();
	Child.prototype.constructor = Child;
	Child.uber = Parent.prototype;
}

function Shape(){}
// augment prototype
Shape.prototype.name = ‘shape‘;
Shape.prototype.toString = function(){
	var result = [];
	if (this.constructor.uber) {
		result[result.length] = this.constructor.uber.toString();//super.toString()
	}
	result[result.length] = this.name;
	return result.join(‘, ‘);
};
function TwoDShape(){}
//先继承。再增强
extend(TwoDShape,Shape);

TwoDShape.prototype.name = ‘2D shape‘;

function Triangle(side, height) {
	this.side = side;
	this.height = height;
}

extend(Triangle,TwoDShape);
Triangle.prototype.name = ‘Triangle‘;
//使用继承而来的toString方法
alert(new Triangle(10,5).toString());