• yarn server to start the server
• yarn start to start the client

The client subscribes to a stream of events sent by the server (Oh, wait ! We could call that "server-sent events" ! 😃).

Once a subscriber is registered, the server sends random strings during 10 seconds, which are displayed by the UI.

• https://medium.com/conectric-networks/a-look-at-server-sent-events-54a77f8d6ff7