I’ve started working on a node-js library for interacting with NetworkManager via DBus. It implements some basic functionality–scanning for access points, connecting to networks, and showing the status of the ethernet/wifi adapters.
It’s definitely a work in progress; NetworkManager has loads more functionality that could be implemented (enterprise networks, cellular modems, etc.).
If you’re interested in using it or contributing, the page is here: https://www.npmjs.com/package/networkmanager-dbus