From your terminal:
git clone https://github.com/omnicoders/node-jwt-api.git
npm install
cd node-jwt-api && node server
In local development, the environment variables are expected to be located in /config/env.js which is not included in the git commit as it contains secure information not to be shared with the public.
In production the environment variables should be applied prior to deployment.
Below is an example that you can fill out and save to /config/env.js:
// /config/env.js
process.env.DB_USERNAME = "myDbUsername";
process.env.DB_PASSWORD = 'myDbPassword';
process.env.DB_URI = 'ds123456.mlab.com:12345/mydbname';
process.env.JWT_SECRET = 'mySuperSecretPasswordPhrase';