Event mechanism in node.js

Node.js is an Event driven like Dom. When user interacts with particular interface, then there is an event.

Node.js created EventEmitter class to provide basic event functionality.

require('events').EventEmitter  to access EventEmitter.
This class contains different events


1.emitter.addListener(event,listener)  or  emitter.on(event, listener)

all the EventEmitters emit event newListener when new listener ads.


session.on(change, function())

session changed.

ex:

server.on(event,function(p,q,r){

});



2. emitter.once(event,listener)

it adds one time listener for event and it invoked only next time event fired.

 3.emitter.removeListener(event,listener)
it removes a listener.

 4.emitter.removeAllListener([event])

it removes all listeners.

5.emitter.setMaxListeners

defaultly it will print warning if more than 10 listeners added to particular event. Set zero for unlimited listeners.

6.emitter.listeners(event)

It returns an array of listeners for an event.

7.emitter.emit(event,arg1[],arg2[],.....)

it executes each listeners in an order.