gistfile1.js

Exposed.prototype._getApplicableNamespaces = function () {
    var namespaces = this.__namespaces__.concat(),
        proto      = Object.getPrototypeOf(this);

    function isApplicable(namespace) {
        return !namespaces.some(function (ns) {
            var nsRegex = new RegExp('^' + ns + '(?:$|\\..+)');
            return nsRegex.test(namespace);
        });
    }

    while (Exposed.isExposed(proto)) {
        namespaces.unshift.apply(namespaces,
                proto.__namespaces__.filter(isApplicable));

        proto = Object.getPrototypeOf(proto);
    }

    return namespaces;
};

I know, performance probably doesn't matter. So, for laughs:

Exposed.prototype._getApplicableNamespaces = function () {
    var namespaces = this.__namespaces__;
        proto      = Object.getPrototypeOf(this);

    function isApplicable(namespace) {
        return !namespaces.some(function (ns) {
            var nsRegex = new RegExp('^' + ns + '(?:$|\\..+)');
            return nsRegex.test(namespace);
        });
    }

    // couldn't think of a better name
    var namespacez = [];
    while (Exposed.isExposed(proto)) {
        namespacez.push.apply(namespacez,
                proto.__namespaces__.filter(isApplicable));

        proto = Object.getPrototypeOf(proto);
    }

    return namespacez.reverse().concat(namespaces)
};

I don't know for certain if this actually works, nor if it really is faster. Both assumptions should be true... in theory.

Oh this actually has to check the whole chain. There's some semantics behind this which aren't obvious, but I documented them in the real code: https://github.com/yahoo/express-state/blob/cache/lib/exposed.js#L118