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