Base: => . Base.prototype.func: string => 'zero/' + string. FirstChild: => . FirstChild extends Base FirstChild.prototype.func: string => super('one/') + string. SecondChild: => . SecondChild extends FirstChild SecondChild.prototype.func: string => super('two/') + string. ThirdChild: => . ThirdChild extends SecondChild ThirdChild.prototype.func: string => super('three/') + string. result: (new ThirdChild()).func('four') print(result is 'zero/one/two/three/four')