Hey,
I am really happy to find out a library that supports html renderning of notation. I am looking forward to creating a machine learning app with React. Would you support drum's notation? Do you believe that this is doable with your js lib by extending it, i feel like trying it :-)
VexFlow does have support for percussion noteheads.
http://public.vexflow.com/tests/ -- search for "Percussion" to see some examples


The code for these tests are in this file https://github.com/0xfe/vexflow/blob/master/tests/percussion_tests.js