This application shows how to use a collaboration between a setTimeout scheduler and the Web Audio scheduler to properly implement rock-solid timing for audio applications.
Check it out, feel free to submit issues or requests, fork, submit pull requests, etc.
Zoe's demo: https://zoeweinberg.github.io/metronome/
The original live app is at http://webaudiodemos.appspot.com/metronome/index.html.
-Chris