Useful Heroku Commands:

heroku create appname
git push heroku master
heroku ps:scale web=1
heroku open
npm init / install —save
foreman start [web]
git add . / commit etc. 
git push heroku master
heroku open
heroku addons:create <addonname>
heroku run node / bash run one-off Dynos(ephemeral)
heroku config:set TIMES=2 (config vars in process.env)
heroku releases (like Git commits)
heroku logs [—ps web.1] [—tail]

Dynos are ephemeral and isolated: always created from slug, and all changes is lost after it closes. For shared resource and communication, use addons