messages-proxy.js

const makeMessages = (src = {}, path = []) =>
    new Proxy(src, {
        get(target, name) {
            const newPath = [...path, name];

            // For _any_ key on messages, return a function that returns the string-path to that key.
            // Also, wrap that function in this proxy to do the same for any key on the function
            return makeMessages(() => newPath.join('.'), newPath);
        }
    });

const messages = makeMessages();