Using Event Emitter in your node modules

app.js

var Fancy = require('FancyModule');

var mod = new Fancy();

mod.on('success', function(data) {
    
    console.log(data); // { this_is_fancy:'indubitably' }
    
});

fancy.js

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

function FancyModule() {

    EventEmitter.call(this);
    
    // And other fancy code

}

FancyModule.prototype = Object.create(EventEmitter.prototype);

FancyModule.prototype.fancified = function() {
    
    // Just one of many fancy functions available in my fancy module
    
    var fancyData = { this_is_fancy:'indubitably' };
    
    this.emit('success', fancyData);
    
}

module.exports = FancyModule;