dkhabiya/EventEmitter

Simple Event Emitter

Event Emitter

A JavaScript event emitter.

Install & Test

• Download repository.
• Run npm install.
• To test - npm test.

Implementation Details

This implememtation has the following methods.

• on

on(event, handler) Adds an event along with a function or handler to be called when the event is fired. It takes the following parameters.

Parameter	Type	Mandatory
event	string	Yes
handler	function	Yes

Usage example:

var Emitter = require('./src/emitter.js');
var e = new Emitter();

var handler = function() {
        console.log("Hello! This is an example.");
}

e.on('Event', handler);

• off

  off(event, handler) Removes events/handlers. It takes the following parameters

Parameter	Type	Mandatory
event	string	No
handler	function	No

Cases:

• Removes all events and handlers when no parameters are sent.
• Removes all handlers of the event, if only event is sent.
• Removes handler mentioned for the event sent.

Usage example:

var Emitter = require('./src/emitter.js');
var e = new Emitter();

var handler = function() {
        console.log("Hello! This is an example.");
}

e.on('Event', handler);
e.off('Event', handler); //Removes handler of 'Event'
e.off('Event'); //Removes all handlers of 'Event'
e.off(); //Removes all events and handlers

• once

once(event, handler) Adds an event along with a function or handler to be called when the event is fired. It takes the following parameters.

Parameter	Type	Mandatory
event	string	Yes
handler	function	Yes

Usage example:

var Emitter = require('./src/emitter.js');
var e = new Emitter();

var handler = function() {
        console.log("Hello! This is an example.");
}

e.once('Event', handler); 

• emit

emit(event, args) Triggers all handlers for the event with the arguments sent. If no arguments are sent the handler is triggered without any parameters.

Parameter	Type	Mandatory
event	string	Yes
args	*	No

Usage example:

var Emitter = require('./src/emitter.js');
var e = new Emitter();

var handler = function() {
        console.log("Hello! This is an example.");
}

e.on('Event', handler);
e.emit('Event');
e.emit('Event', 5, 8);