This index is pretty lo-fi. I've spent a lot more time on the resources below.
HTML Canvas
Pong
The guide through this arcade classic starts with a static Pong Example with HTML5 Canvas, following from which there are increasingly advanced stages of a pong game, all the way to a playable Pong game.
Time
Dive into
Time in JavaScript
with this one-page introduction which looks at
setTimeout, setInterval, and building
stopwatches.
Special Effects
The Loki "pruning" game based on the Marvel Studios TV series looks in depth at how complex visual effects can be created in steps.
HTML Audio
Learning HTML5 Audio with Velociraptors
An introduction to the HTML5 audio element, featuring a memorable dinosaur sound.
Learning how to create HTML5 Audio controls
A more advanced guide to HTML5, looking at how to use the default controls and provide custom functionality.
HTML Basics
Semantic and Non-Semantic HTML
Two pages which look identical, but one is using semantic HTML and the other using non-semantic HTML
Happy travels!
Robin