[JangoSteve]

Cool demo! I like that you can see all the events in real-time. I built a similar demo (https://os.alfajango.com/websockets-demo/ and https://github.com/JangoSteve/websockets-demo) a while ago to showcase using websockets with a node app for a presentation I was giving at a JavaScript user group (https://os.alfajango.com/websockets-slides/).

The presentation goes through a bit of the history and lead-up to websockets for context.

One of my favorite things about the demo for the presentation was that everyone in the room (probably about 50 people) was able to connect to the live demo in real-time and some people started finding XSS vulnerabilities in it right away, and using the app to send emojis and pictures to others in the room in real-time (all harmless stuff). It was crazy though how many events you could see streaming through the app just running from my laptop with so many people connected and interacting at once (including x,y coordinates for mouse movements a few times per second per user as well).

The presentation goes through alternatives as well, including long-polling, short-polling, and server-side events (the slides are laid out in two dimensions, so pay attention to when you can hit the "down" arrow instead of the "right" arrow for more slides). It also delves a bit into the actual websocket spec. It was a while ago though, so it doesn't go into anything HTTP2-related.