Audio in the browser is deceptively tetchy. It's easy to get a basic sound to play with the .[code=html:1] But there are several problems with this:
First of all, good luck navigating this compatibility chart. Until Mozilla finally caved and decided to support MP3, there was no single file format supporting Chrome, Firefox, Safari, and IE. Opera is still a painful holdout on file formats, and the situation on mobile is disgusting.
You can't programmatically trigger the audio playing on mobile devices without direct user action in your game loop. You basically have to put up a "start game" button that tricks the user into playing a silent audio file, then you have free reign to trigger that particular audio element.
You get almost no control over how the file plays. There is a volume setting, but it hasn't always been reliable on all platforms. There's no mixing. There are no effects.
It's super difficult to rewind and replay an audio file. Honestly, I still don't really know how to do it correctly, and I'm a goddamn salty pirate.