stateful-event

a tiny stateful eventbus in few lines of js

Usage

var se = require('stateful-event')

var bus   = new se()
bus.debug = true                                      // will output publish() calls in console

var x = bus.subscribe("someprocess/start", function(data, state){
  if( state == "offline" ) return
  // do stuff 
})

bus.subscribe("state", function(state){
  if( state == "online"  ) console.log("fooooo!")
  if( state == "cleanup" ) bus.unsubscribe(x)
})

bus.state("online")                                   // sets state to online 
bus.publish("someprocess/start",{foo:"bar"})          // will fire doFoo()
bus.state("offline")                                  // set state to online
bus.publish("someprocess/start",{foo:"bar"})          // won't fire doFoo
bus.publish("someprocess/start",{foo:"bar"},"online") // set state to "online", and will fire doFoo
bus.publish("someprocess/start",{foo:"bar"})          // will fire doFoo()
console.log( bus.state() )                            // will return "online"
bus.state("cleanup")                                  // will trigger bus.unsubscribe(x)

user login state management:

var bus   = new se({defaultstate:"loggedout"})

function sessionExpired() {
  bus.state( bus.opts.defaultstate = "loggedout" )
}

login( user, pw, sessionExpired, function(){
  bus.state( busopts.defaultstate = "loggedin" )
})

hint: for (arguably) more pretty code, you could use string-variables named like ONLINE instead of "online"

Features

• event listening and triggering
• be able to unsubscribe or ignore events in certain state
• easier to use / extendable compared to EventEmitter
• maintain state in bus instead of global scope

Functions

bus.state(state)                  // set/get state: state("mystate") or state() returns current state-string
bus.publish(channel, data, state) // publish: publish('some/channel', ['Denis', 'Ciccale'], "mystate" // optional )
bus.subscribe(channel, handler)   // usage: var handle = subscribe('some/channel', function (name, lastName) {})
bus.unsubscribe(handle)           // usage: unsubscribe(handle);