JavaScript: force the order in which function properties of a module can be called.

Question

I wish to create an API that can be called in the following fashion:

var f = foo().bar().barAgain().barTheThird();

but not:

var f2 = foo().bar().barTheThird();

barAgain() can only be called after calling bar(), barTheThird() can only be called after calling barAgain() and so on.

function foo() {
    var that = {};

    var _bar = function () {
        return that;
    };

    var _barAgain = function () {
        return that;
    };

    var _barTheThird = function () {
        return that;
    };

    _barAgain.barTheThird = _barTheThird;
    _bar.barAgain = _barAgain;

    that.bar = _bar;

    return that;
};

The above does not work. foo().bar() is called via the method invocation pattern, therefore the keyword this is bound to the object that within _bar.

I have found one solution:

var _bar = function () {
    that.barAgain = _barAgain;
    delete that.bar;
    return that;
};

But this does not feel particularly clean or elegant.

Has anyone come across this sort of problem before? Any suggestions for a more elegant solution?

Thanks in advance!