WorkEmitter

WorkEmitter.js

// problem: you need to emit an event and then do something AFTER the handlers have completed
// EventEmitter works ONLY if your event handlers are not async. If you're working in the browser and you
// emit an event and then change page, or submit a form, you run the risk of your async handlers not completing
// before you change pages

// WorkEmitter has the same interface as EventEmitter, except it expects that the handlers will return a promise.

var Q = require('q')
emitter.on('submit', function(form) {
  var deferred = Q.defer()
  // some async function
  form.validate(function(err) {
    if (err) {
      return deferred.reject(err)
    }
    deferred.resolve()
  })
  return deferred.promise
})

emitter.emit('submit', form).then(function() {
  // something to do after all events on "submit" have completed successfully
}).fail(function(err) {
  // something to do after one or more events on "submit" have errored
}).fin(function() {
  // something to do after all events have been processed
})

Thinking about adding priorities to this as well.

emitter.on(-1000, 'submit', function() {
  // high priority
})

// normal priority, both will be run in parallel because they share the same priority
emitter.on('submit', function(){})
emitter.on('submit', function(){})

// low priority
emitter.on(9001, 'submit', function(){})

event handler execution flow:

[-1000 handler]
Then
[normal handler, normal handler] (in parallel)
Then
[9001 handler]