My conjecture: Scheduling with priority is pretty easy across these systems. The dependency graph transfer would be outside the scope of what they already tackle, and require new engineering.

In Pyret, I prototyped virtual threads at one point, and each thread had the same amount of "fuel" before yielding (at the top of every compiled function in Pyret, there's a decrement to a "fuel" counter, and when it reaches zero, the stack is unwound). That could easily be configured on each start/restart of a thread to provide different amounts of fuel, or to re-order the restarts based on typical thread-scheduling policies.

Whalesong does the same thing with fuel, so I imagine it could be extended similarly.

I don't know how Doppio and GopherJS do scheduling in detail, but here's where I'd start looking:

1. GopherJS looks like it's a simple queue based on the code around https://github.com/gopherjs/gopherjs/blob/master/compiler/pr... (goroutines push themselves onto a list when they pause, then the next one starts up again)

2. Doppio implements a thread pool abstraction, so you can simulate JVM threads in the browser: https://github.com/plasma-umass/doppio/blob/master/src/threa...