extended-emitter

extended-emitter.js
===================


[//]: # (Old travis link went here, replace with actions based build)

Everything you expect from require('events').EventEmitter in both the browser and client, plus:
- criteria : use a sift expression to work on a subset of the events
- .allOff() : removes all events from this emitter
- .emitter : the internal emitter used, in case you need direct access.

import
------
CommonJS
``javascript
const { Emitter } = require('extended-emitter');
const emitter = new Emitter();
`
ES6 imports
`javascript
import { Emitter } from 'extended-emitter';
const emitter = new Emitter();
`

optional criteria
-----------------
you can now using mongo-style queries (supported by sift) to subscribe to specific events (in this context .once() means meeting the criteria, not just firing an event of that type).

`javascript
emitter.on('my_object_event', {
myObjectId : object.id
}, function(){
//do stuff here
});

// or

emitter.once('my_object_event', {
myObjectId : object.id,
myObjectValue : {
$gt : 20,
$lt : 40
}
}, function(){
//do stuff here
});
`

.when()
-------

and there's also the addition of a when function which can take ready-style functions, real promises or events, making it easy to delay or wait for a state, without resorting to chaining.

$3


`javascript
await emitter.when([$(document).ready, 'my-init-event', 'my-load-event']);
`

$3

`javascript
emitter.when([$(document).ready, 'my-init-event', 'my-load-event'], function(){
//do stuff
});
`

.onto()
-------
Often you want an object to implement emitters, and while it's easy enough to wrap them, why not just have that done for you and avoid the boilerplate?

`javascript
emitter.onto(MyClass.prototype);
emitter.onto(MyInstance);
emitter.onto(MyObject);
`

or in the constructor:

`javascript
(new Emitter()).onto(this);
`

Testing
-------

Run the tests at the project root with:

`bash
npm run import-test
npm run require-test
``

Enjoy,

-Abbey Hawk Sparrow