One thing not mentioned in the article: you don't have to render everything on a single canvas, you can use multiple canvases as layers. This is specially useful to separate what is updated often with what changes rarely, for instance the characters layer, the background layer and the HUD layer can potentially have very different update rates, so it makes sense to redraw them at a different pace each. In fact, you can also get creative and combine DOM elements with canvases.

These tricks matter because redrawing the entire screen every frame is usually an expensive operation; this is not noticable on small examples but it can become an issue on larger, more complex games.

Great article otherwise.