util-eventemitter

A helpful, efficient and lightweight util - event emitter.

Install

npm i util-eventemitter

or

npm i util-eventemitter --save

Usage

var { Emitter } = require('util-eventemitter');
var em = new Emitter(); 

var callbackFn = function () {};

//listener
em.on('foo', callbackFn);
em.addEventListener('foo', callbackFn);

//one time listener
em.once('bar', callbackFn);
em.addOneTimeListener('bar', callbackFn);

//emit
em.emit('foo', ...arg);

//remove listener
em.off('bar', callbackFn);
em.removeListener('bar', callbackFn);

//clear all listeners 
em.removeAll();
em.removeAllListeners();

//check number of existing events
em.count();

//check number of listeners under the specific event
em.count('event name');

Alternatively, you can using emitter directly as imported module without initialization, as it is initialized.

var { emitter } = require('util-eventemitter');

//no need to initialize, use it directly same as above

Method

on(event, fn) , addEventListener(event, fn)

• event - the name of the event
• fn - a callback function to trigger when event is emitted(listener)

once(event, fn) , addOneTimeListener(event, fn)

• event - the name of the event
• fn - a callback function to trigger when event is emitted

This listener only trigger listener only once

emit(event[, ...payload])

• event - the name of the event
• ...payload[optional] - a series of arguements pass to the listener

off(event[, fn]) , removeListener(event[, fn])

• event - the name of the event
• fn - a listener

removeAll() , removeAllListeners()

count(event)

• event[optional] - the name of the event

If event is skipped, returns number of events, otherwise it returns number of existing listeners for specific event

Tests

npm install
npm test

Build

npm install
npm run build

License

MIT