Reading 16 - AvreyBrown-401-advanced-javascript/seattle-javascript-401d32 GitHub Wiki

Node.js core API is based on asynchronous event-driven architecture in which certain kind of objects called emitters periodically emit events that cause listener objects to be called.

const EventEmitter = require('events'); class MyEmitter extends EventEmitter {} const myEmitter = new MyEmitter(); myEmitter.on('event', function(a, b) { console.log(a, b, this); // Prints: // Technoetics Club MyEmitter { // domain: null, // _events: { event: [Function] }, // _eventsCount: 1, // _maxListeners: undefined } }); myEmitter.emit('event','Technoetics', 'Club'); Here we create a myEmitter object and emit event at the end which triggers the callback function and we are able to get the desired output. By default, all listeners attached to a particular event object are called by the EventListener object synchronously in the order in which they are registered or attached to the event object.

Event-Driven Programming is a logical pattern that we can choose to confine our programming within to avoid issues of complexity and collision. In this article we’re going to go over how Event-Driven Programming works and how we can make the best use of it in our Node.js projects.

Most developers are introduced to concepts of Event-Driven Programming early on in their study of programming yet they might not fully realize it until a bit later. You’ll find that the concept is rather ubiquitous. Check any major framework or software out there and odds are you’ll find evidence of Event-Driven Programming.