theme that does some initialization when you join a channel

[phaedryx]

I'm working on a limechat theme and I'd like it to do a bit of setup
for me when I enter a channel. I've tried using javascript:
window.onload, document.onload,
document.addEventListener("DOMContentLoaded",... but nothing I can
think of seems to work. Is there a theme that runs a bit of
javascript when you join a channel that I could look at? Any reason
the methods I've tried so far won't work? Any alternate suggestions?

Thanks.