It's a really good question, and I originally [0] actually had some code that would randomise the sub domain. You can still do this if you host it yourself.

But I think it's probably not nessisary so long as your users are not using indexDB (or any other data storage on that domain), as there should be no other way for the web workers to communicate with each other.

0. https://github.com/markwylde/workerbox/blob/master/lib/index...