chat-engine
Version:
150 lines (117 loc) • 4.22 kB
JavaScript
// Allows us to create and bind to events. Everything in ChatEngine is an event
// emitter
const EventEmitter2 = require('eventemitter2').EventEmitter2;
/**
* The {@link ChatEngine} object is a RootEmitter. Configures an event emitter that other ChatEngine objects inherit. Adds shortcut methods for
* ```this.on()```, ```this.emit()```, etc.
* @class RootEmitter
*/
class RootEmitter {
constructor() {
/**
* @private
*/
this.events = {};
/**
Handy property to identify what this class is.
@type String
@private
*/
this.name = 'RootEmitter';
/**
Create a new EventEmitter2 object for this class.
@private
*/
this.emitter = new EventEmitter2({
wildcard: true,
newListener: true,
maxListeners: 50,
verboseMemoryLeak: true
});
// we bind to make sure wildcards work
// https://github.com/asyncly/EventEmitter2/issues/186
/**
Private emit method that broadcasts the event to listeners on this page.
@private
@param {String} event The event name
@param {Object} the event payload
*/
this._emit = this.emitter.emit.bind(this.emitter);
/**
Listen for a specific event and fire a callback when it's emitted. This is reserved in case ```this.on``` is overwritten.
@private
@param {String} event The event name
@param {Function} callback The function to run when the event is emitted
*/
this._on = this.emitter.on.bind(this.emitter);
/**
* Listen for a specific event and fire a callback when it's emitted. Supports wildcard matching.
* @method
* @param {String} event The event name
* @param {Function} cb The function to run when the event is emitted
* @example
*
* // Get notified whenever someone joins the room
* object.on('event', (payload) => {
* console.log('event was fired').
* })
*
* // Get notified of event.a and event.b
* object.on('event.*', (payload) => {
* console.log('event.a or event.b was fired').;
* })
*/
this.on = (event, callback) => {
// emit the event from the object that created it
this.emitter.on(event, callback);
return this;
};
/**
* Stop a callback from listening to an event.
* @method
* @param {String} event The event name
* @example
* let callback = function(payload;) {
* console.log('something happend!');
* };
* object.on('event', callback);
* // ...
* object.off('event', callback);
*/
this.off = (event, callback) => {
// emit the event from the object that created it
this.emitter.off(event, callback);
return this;
};
/**
* Listen for any event on this object and fire a callback when it's emitted
* @method
* @param {Function} callback The function to run when any event is emitted. First parameter is the event name and second is the payload.
* @example
* object.onAny((event, payload) => {
* console.log('All events trigger this.');
* });
*/
this.onAny = (event, callback) => {
// emit the event from the object that created it
this.emitter.onAny(event, callback);
return this;
};
/**
* Listen for an event and only fire the callback a single time
* @method
* @param {String} event The event name
* @param {Function} callback The function to run once
* @example
* object.once('message', => (event, payload) {
* console.log('This is only fired once!');
* });
*/
this.once = (event, callback) => {
// emit the event from the object that created it
this.emitter.once(event, callback);
return this;
};
}
}
module.exports = RootEmitter;