strict-event-ordering.js

var events = require('events');
var simpleBus = new events.EventEmitter();

var strictlyOrderedBus = {};
strictlyOrderedBus.bus = simpleBus;
strictlyOrderedBus.emit = function(evt) { setImmediate(this.bus.emit.bind(this.bus), evt); }
strictlyOrderedBus.on = simpleBus.on

var globalBus;

function func1() {
  console.log("func1: start");
  globalBus.emit("event2");
  console.log("func1: end");
}

function func2() {
  console.log("func2: start");
  console.log("func2: end");
}

function func3() {
  console.log("func3: start");
  console.log("func3: end");
}

globalBus = simpleBus;

globalBus.on("event1", func1);
globalBus.on("event1", func2);
globalBus.on("event2", func3);

console.log("triggering event1 on simpleBus");
globalBus.emit("event1");

globalBus = strictlyOrderedBus;
console.log("triggering event1 on strictlyOrderedBus");
globalBus.emit("event1");