This example is based on the Google+ Sign-In "one-time-code" flow (sometimes known as the "hybrid flow") for authentication. This is documented at https://developers.google.com/+/web/signin/server-side-flow and the steps mentioned in the files here correspond to the steps outlined there.
This is considered best practice if you want the user to sign-in using the Google+ Sign-In button, but wish to be able to take actions on the user's behalf from the server, or after they are not active at your site. See the page at http://developers.google.com/+/ for further details.
As documented in Step 1, you will need to create a project with the Google APIs Console. From this console, you will need to generate a Client ID and Secret, which you will need to provide when running the app.
All dependent npm packages are defined in package.json, so you should run
npm install
to have the dependencies automatically downloaded and installed.
The id and secret that you received from the developers console will be passed to the program using environment variables. In UNIX-derived operating systems, you can replace them inside the quotes in a command such as:
CLIENT_ID="id" CLIENT_SECRET="secret" node app.js
You can then connect to the server from a web browser and click on the Sign-In button.
Most of the output will be logged to either the node.js console or the browser's javascript console, and can be useful to understand what tokens are being received and how they are handled.
Questions, comments, suggestions, and feedback of all sorts are welcome. You can either submit a bug or change via github at https://github.com/afirstenberg/google-plus-node, ask a question via the Google+ Developers community on Google+, or find me on Google+ at http://plus.prisoner.com/