NJ-Events

Simple and light-weight event emitter library for JavaScript.

• No dependencies, less than 1KB pure JavaScript implementation.
• on method returns an ID. Use this ID to remove specific listener or the event-name to remove all the listeners.
• No aliases, just emit, on and off methods.

const emitter = new NJEvents();
const id = emitter.on('hey', data => {
  console.log(data);
});
emitter.emit('hey', 'how are you?');
emitter.off(id);

Installation

npm install --save nj-events

You can use NJEvents as an ES6 module as follows:

import NJEvents from 'nj-events';
const emitter = new NJEvents();

Alertnatively you can include the script.js script before the closing </body> tag and then in your JS create a new instance of NJEvents as below.

<script src="path/to/script.js"></script>
<script>
    const emitter = new NJEvents();
</script>

Usage

NJ-Events are driven by the on, emit, off methods which are detailed below.

Registering an event

• on() - the listener is registered and will be active until removed explicitly.
• once() - the listener is removed after first trigger.
• both methods take an event_name:string, callback:function and an optional id:string as parameters.
  ```js
  const emitter = new NJEvents();

const id_on = emitter.on(‘hey’, data => { // listener is registered until removed
console.log(data);
});

const id_once = emitter.once(‘hey’, data => { // listener is removed after first trigger
console.log(data);
});

const custom_id = emitter.on(‘hey’, data => { // init with custom id
console.log(data);
}, YOUR_CUSTOM_ID);

### Triggering an event
An event is triggered using the `emit()` by passing the `event_name:string` and `data:any`
```js
emitter.emit('hey', 'how are you?');

Unregistering an event

An event can be unregistered using the off() with the below parameters

• event_name - any matching events and its listeners will be removed.
• id - event with the particular id will be removed, the event would still exist.

  emitter.off('hey'); // unregister using event-name 
  emitter.off(id); // unregister using the event ID

  Releases and Changes

  Check out the Releases and Change Logs for more information.

Copyright and License

The MIT license