CONTENT


var a = {
    x: 10,
    y: 10,
    calculate: function(z) {
        return this.x + this.y + z;
    }
};


var b = {
    y: 20,
    _proto_: a
};


var c = {
    y: 30,
    _proto_: a
};


b.calculate(30);//60
c.calculate(40);//80

亲自来试一试吧?