Node.js has multiple in-built events available through events module and EventEmitter class which is used to bind events.
EventEmitter provides multiple properties like on and emit. on property is used to bind a function with the event and emit is used to fire an event.
Below is an example :
Step 1: Run "npm init"
Step 2 : Insert all required parameter in 'npm init' and create the start page 'index.js'.
Step 3: index.js will be as below
// Import events module
var events = require('events');
// Create an eventEmitter object
var eventEmitter = new events.EventEmitter();
// Create an event handler as follows
var connectHandler = function connected() {
console.log('connection succesful.');
// Fire the data_received event
eventEmitter.emit('data_received');
}
// Bind the connection event with the handler
eventEmitter.on('connection', connectHandler);
// Bind the data_received event with the anonymous function
eventEmitter.on('data_received', function(){
console.log('data received succesfully.');
});
// Fire the connection event
var eventListeners = require('events').EventEmitter.listenerCount(eventEmitter,'connection');
console.log(eventListeners + " Listner(s) listening to connection event");
eventListeners = require('events').EventEmitter.listenerCount(eventEmitter,'data_received');
console.log(eventListeners + " Listner(s) listening to data_received event");
console.log("Listner Count Ended...............");
eventEmitter.emit('connection');
console.log("Connection Event Ended...............");
eventEmitter.emit('data_received');
console.log("data_received Event Ended...............");
eventEmitter.removeAllListeners();
eventEmitter.emit('connection');
console.log("Program Ended...............");
Step 5: Run the application by 'node index.js' and see the responses in console.
