Node Emitter Example

gistfile1.txt

/**
 * Created by dm on 2/22/17.
 */
'use strict';

// Set Up a Node Global OnOff Emitter
const events = require('events');
if (!global.OnOffEmitter) {
  global.OnOffEmitter = new events.EventEmitter();
}

// OnOff Class name=device name, emitter is the emitter

class OnOff {

  constructor(name, emitter) {
    this.name = name;
    this.state = 'off';
    this.emitter = emitter;
  }

  on() {
    this.state = 'on';
    this.emitter.emit('on', this.name+' '+this.state);
    return this.state;
  }

  off() {
    this.state = 'off';
    this.emitter.emit('off', this.name+' '+this.state);
    return this.state;
  }

}


// Construct Two Devices
const onOffLight = new OnOff('light', global.OnOffEmitter);
const onOffCar = new OnOff('car', global.OnOffEmitter);

// Listen when On
global.OnOffEmitter.on('on', (state)=>{
  console.log(state);
});

// Listen when Off
global.OnOffEmitter.on('off', (state)=>{
  console.log(state);
});

global.OnOffEmitter.on('error', (err) => {
  console.log('whoops! there was an error', err);
});

// Run a few Tests
onOffLight.on();
onOffLight.off();
onOffLight.on();
onOffLight.off();
onOffLight.on();
onOffLight.off();
onOffLight.on();
onOffLight.off();

onOffCar.on();
onOffCar.off();
onOffCar.on();
onOffCar.off();
onOffCar.on();
onOffCar.off();
onOffCar.on();
onOffCar.off();

global.OnOffEmitter.emit('error', new Error('Whoops!'));