function A() {}
A.foo = "foo";
A.prototype = {bar: function () { return "bar"; }};

function B() {}
B.baz = "baz";
B.prototype = new A();
B.prototype.qux = function () { return "qux"; };

var b = new B();
b.quo = "quo";

console.log(b.quo);    //-> "quo"
console.log(b.qux());  //-> "qux"
console.log(b.baz);    //-> undefined
console.log(B.baz);    //-> "baz"
console.log(b.bar());  //-> "bar"
console.log(b.foo);    //-> undefined
console.log(B.foo);    //-> undefined
console.log(A.foo);    //-> "foo"