Async event emitter

gistfile1.md

What I'm considering for an async event emitter is a situation like this:

1. I want to be able to fire events before something happens and after something happens.
2. Each of the event handlers may do an async process.
3. I need to know after all of the "before" event handlers have completed before doing the actual action that I'm saying will happen.

A synchronous example would look like:

emitter.emit('beforewrite');
doWrite();
emitter.emit('afterwrite');

The challenge is that the event handlers may all be doing async operations, so I need to wait until all of them have completed before doing the write operation.

Thoughts?

I wrote a library a while ago to do exactly this: https://github.com/shesek/emit-async