neva
v1.0.2
Published
Simple library to work with custom events.
Downloads
10
Maintainers
Readme
neva
Simple library to work with custom events.
- Simple event emitter API:
on
,off
,emit
,hasEventHandler
. - Event emitter API is chainable.
- Events can be emitted with multiple attached parameters.
- Data about emitted event are wrapped into an object with uniform structure that is passed to handlers.
- Ability to add event handler that should be called just once.
- Ability to enhance prototype of constructor function (class) with event emitter API (emitter methods can be mixed in
prototype
). - Available as ECMAScript 6/2015 module, CommonJS module or UMD.
- Work in any ECMAScript 3+ environment (browsers, Node.js etc).
- Small.
Table of contents
Installation ↑
Node
npm install neva
Bower
bower install neva
AMD, <script>
Use dist/neva.js
or dist/neva.min.js
(minified version).
Usage ↑
ECMAScript 6+
import getEmitter from 'neva';
Node
const getEmitter = require('neva').getEmitter;
AMD
define(['path/to/dist/neva.js'], function(neva) {
const getEmitter = neva.getEmitter;
});
Bower, <script>
<!-- Use bower_components/neva/dist/neva.js if the library was installed by Bower -->
<script type="text/javascript" src="path/to/dist/neva.js"></script>
<script type="text/javascript">
// neva is available via neva field of window object
const getEmitter = neva.getEmitter;
</script>
Examples ↑
const emitter = getEmitter();
const eventHandler = (event) => {
console.log('eventHandler: event type -', event.type, ', data -', event.data);
};
const obj = {
name: 'obj',
handler(event) {
console.log(`${this.name}.handler: event type -`, event.type, ', params -', event.params);
}
};
function onceHandler(event) {
console.log('onceHandler: event type -', event.type, ', data -', event.data);
}
emitter.on(['event1', 'event2'], eventHandler)
.on('event1', obj.handler, obj)
.on('event2', onceHandler, null, {once: true});
emitter.emit('event1', 1, 2, 3)
.emit({type: 'event2', data: 'some data', qty: 8});
// The following will be printed into console:
// eventHandler: event type - event1 , data - 1
// obj.handler: event type - event1 , params - Array [ 1, 2, 3 ]
// eventHandler: event type - event2 , data - some data
// onceHandler: event type - event2 , data - some data
emitter.hasEventHandler('event1', eventHandler); // true
emitter.hasEventHandler('event2', onceHandler); // false
emitter.off('event1', eventHandler);
emitter.hasEventHandler('event1', eventHandler); // false
emitter.hasEventHandler('event1'); // true
emitter.off('event1');
emitter.hasEventHandler('event1'); // false
emitter.hasEventHandler(); // true
emitter.off();
emitter.hasEventHandler(); // false
class SomeClass {
...
}
// Add event emitter methods to class
getEmitter(SomeClass.prototype);
API ↑
getEmitter([target: Object]): EventEmitter
Create event emitter or add methods to work with events into specified object.
target
can be prototype of some constructor function (class).
EventEmitter API
on(type: string | string[], handler: Function, [context: Object], [settings: HandlerSettings]): EventEmitter
Register a handler for the specified event type(s).
off(type: string, handler: Function, [context: Object]): EventEmitter
Remove the specified event handler.
off(type: string): EventEmitter
Remove all handlers for the given event type.
off(): EventEmitter
Remove all registered event handlers.
emit(type: string, [param1: any, param2: any, ...]): EventEmitter
Call all handlers for the specified event type.
An object with the following fields will be passed in each handler:
type: string
- the event type (value oftype
parameter).params: Array
- list of additional parameters that are passed besides the event type ([param1, param2, ...]
).data: any
- value of the second function's parameter (value ofparams[0]
).
emit({type: string, ...}): EventEmitter
Call all handlers for the specified event type and pass the given object in each handler.
hasEventHandler(type: string, handler: Function, [context: Object]): boolean
Check whether the specified event handler is registered.
hasEventHandler(type: string): boolean
Check whether any handler for the specified event type is registered.
hasEventHandler(): boolean
Check whether any event handler is registered.
See docs
for details.
Contributing ↑
In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.
License ↑
Copyright (c) 2017-2021 Denis Sikuler
Licensed under the MIT license.