Comment by FjordWarden

Ok, the EventTarget is a very cute trick and I haven't thought much about implementing signals this way. However, all "serious" signal libraries have at least computed (higher order signals), and a way to sample a value, meaning get the value from a signal without triggering its effects, and no you can't just call foo.value because this won't work with computed signals, and a way to batch multiple write calls to multiple signals, which is often implemented by swapping the effects in and out of the update phase of the signal.