Node.js Events

Node.js Events

Every action on a computer is an event. Node.js object can fire an event like readStream object fires events when opening and closing a file.

 var fs = require('fs');  
 var rs = fs.createReadStream('./demo.txt');  
 rs.on('open', function () {  
    console.log('The file is open');  
 });  
   

Events Module

Node.js has a built-in module, called "Events", where you can create-, fire-, and listen for- your own events. All event properties and methods of event module are an instance of an EventEmitter object.

EventEmitter Object

 var events = require('events');  
 var eventEmitter = new events.EventEmitter();  
   
 //Create an event handler:  
 var myEventHandler = function () {  
    console.log('I hear a scream!');  
 }  
   
 //Assign the event handler to an event:  
 eventEmitter.on('scream', myEventHandler);  
   
 //Fire the 'scream' event:  
 eventEmitter.emit('scream');  
   

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