ES6-Class-Extends.js

//example by Anthony Alicea
//Inheriting from the Event Emitter using util.inherits

var EventEmitter = require('events');

class Greetr extends EventEmitter {
  //any method inside constructor is available directly to any instance object 
  //super() calls the superconstructor (EventEmitter) we are inheriting from
	constructor() {
		super();
		this.greeting = 'Hello world!';
	}
	
  //add a greet method on the prototype
	greet(data) {
		console.log(this.greeting + data);
		this.emit('greet', data);
	}
}

//create a new object greeter1
var greeter1 = new Greetr();

//we can now also use emit because Greetr is inheriting from EventEmitter
greeter1.on('greet', function(data) {
	console.log('Someone greeted!: ' + data);
});

greeter1.greet('Jane');
//Hello World!: Jane
//Someone greeted!: Jane