Canvas is not the only option. I'm currently developing a racing game where you can build your own race track in HTML5 with my colleagues for our final university project and we don't use canvas at all.

The whole game is built upon SVG, CSS3 (transform3d) and CoffeeScript and it works pretty fine, even on the iPad which is also the target platform. The limiting factor with this combination is the number of DOM elements. We are currently considering to render our racing tracks as a single image so we can remove the several SVG paths we currently use for this.

If you want to take a look you can find the source on GitHub[1] or play the game[2]. Currently only Chrome and iPad are supported. But that's only because we haven't added all vendor prefixes yet.

[1] https://github.com/stravid/slotcars [2] http://slotcars.herokuapp.com/

Canvas mostly works across browsers but there are still variances and browser-specific edge cases you have to detect. Cross-browser audio is an absolute trainwreck, and APIs like gamepad, fullscreen, etc. are all very finicky as well and will require careful effort if you want to use them in each browser. Plus, each JavaScript runtime has things it likes/doesn't like so to get playable performance for a serious game in all the browsers you'll have to spend a while figuring out how to tune your JS for all of them (or writing browser-specific versions). This is made worse by the fact that some of the major browsers don't have usable profiling tools...

But sure, if all you want to do is draw some lines and bitmaps on the screen, no problem.