NodeSSH
NodeSSH is a SSH client for node.js. I would call it lightweight, but since it spawns subprocesses, this makes it heavyweight to me. It uses OpenSSH and expect. Make sure you have installed this software.
Use your system's built-in package manager (apt-get,yum,rpm,dselect,etc..) to install expect on you machine. Most systems (OSX included) should already have this installed. This will not work with windows machines.
How to use
Check out the file "sample.js". It should help show you all you need ;) A better version with node-expect is in betterSample.js