Hasan Setiawan

Javascript Event Emitter With your Barehand (Node.js)

I just want to show you very simple code to explain how does EventEmitter works in Node.js.

            
>$ var event = require('events').EventEmitter;
undefined

//create new EventEmitter object
>$ var greeting = new event();
undefined

// registering new event using keyword `on` with callback function and params
>$ greeting.on('sayHello', function(person) {
... console.log(`hello ${person}!`);
... }
... );
EventEmitter {
  domain:
   Domain {
     domain: null,
     _events: { error: [Function] },
     _eventsCount: 1,
     _maxListeners: undefined,
     members: [] },
  _events: { sayHello: [Function] },
  _eventsCount: 1,
  _maxListeners: undefined }

//calling Event using keyword `emit` with parameter to be passed into callback function
>$ greeting.emit('sayHello', 'Jono');
hello Jono!
true