subscribe
v3.0.0
Published
A simple better event emitter
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Kucukkanat's Emitter
Table of Contents
Install
This project uses node and npm. Go check them out if you don't have them locally installed.
$ npm install --save subscribe
// using ES6 modules
import { Emitter } from 'subscribe'
// using CommonJS modules
var { Emitter } = require('subscribe')
The UMD build is also available on unpkg:
<script src="https://esm.sh/subscribe"></script>
You can find the library on window.__Emitter__
.
Usage
import {Emitter} from 'subscribe'
// OR
const {Emitter} = require('subscribe')
const eventbus = new Emitter()
// listen to an event
eventbus.on('foo', e => console.log('foo', e) )
// listen to all events
// This will fire first the 'type' event if it exists
eventbus.on('*', (type, e) => console.log(type, e) )
// fire an event
eventbus.emit('foo', { a: 'b' })
// working with handler references:
function onFoo() {}
eventbus.on('foo', onFoo) // listen
eventbus.off('foo', onFoo) // unlisten
// remove all listeners for specific event
eventbus.off('foo')
// Fire event listener only once
eventbus.once('knock knock', (data) => console.log("I will be fired only once"))
eventbus.emit('knock knock', null)
// This will not fire
eventbus.emit('knock knock', null)
Typescript
For better autocompletion Emitter class takes parameters for possible event names :
import {Emitter} from 'subscribe'
const emitter = new Emitter<'foo' | 'bar'>()
emitter.on('foo', e => console.log('foo', e) )
emitter.on('bar', e => console.log('foo', e) )
// Will throw an error: (on typescript typecheck NOT ON RUNTIME!)
emitter.on('bar2', e => console.log('foo', e) )
API
Table of Contents
constructor
Use the constructor to initiate the eventbus with handlers
Parameters
- ``
listeners
EventHandlerMap
on
Register an event handler for the given type.
Parameters
type
String Type of event to listen for, or"*"
for all eventshandler
Function Function to call in response to given event
off
Remove an event handler for the given type.
Parameters
type
String Type of event to unregisterhandler
from, or"*"
handler
Function Handler function to remove
emit
Invoke this.listeners handlers for the given type.
If present, "*"
handlers are invoked after type-matched handlers.
Note: Manually firing "*" handlers is not supported.
Parameters
type
String The event type to invokeevt
Any? Any value (object is recommended and powerful), passed to each handler
Reporting Issues
Found a problem? Want a new feature? First of all see if your issue or idea has already been reported. If don't, just open a new clear and descriptive issue.