oop - javascript inheritance from multiple objects

Question

I'm not very well aquainted with javascript inheritance, and I'm trying to make one object inherit from another, and define its own methods:

function Foo() {}
Foo.prototype = {
    getColor: function () {return this.color;},
};
function FooB() {}
FooB.prototype = new Foo();
FooB.prototype = {
    /* other methods here */
};

var x = new FooB().getColor();

However, the second one overwrites the first one(FooB.prototype = new Foo() is cancelled out). Is there any way to fix this problem, or am I going in the wrong direction?

Thanks in advance, sorry for any bad terminology.

Answer 1

Each object can only have one prototype, so if you want to add to the prototype after inheriting (copying) it, you have to expand it instead of assigning a new prototype. Example:

function Foo() {}

Foo.prototype = {
    x: function(){ alert('x'); },
    y: function(){ alert('y'); }
};

function Foo2() {}

Foo2.prototype = new Foo();
Foo2.prototype.z = function() { alert('z'); };

var a = new Foo();
a.x();
a.y();
var b = new Foo2();
b.x();
b.y();
b.z();