Is it possible to extend setWatch to include timer interrupts?

Calling a.emit from Assembler is something that just isn't possible at the moment - hence why you need to do the pin joining and setWatch thing.

One issue is that JS functions don't exist as something you can just 'jump' to from Assembler, but also the JS interpreter isn't designed to be reentrant... Even allocating JS vars (for instance the string 'hello') can be a pain.