/**
* Copyright (c) 2000-present Liferay, Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 2.1 of the License, or (at your option)
* any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*/
export default class EventEmitter {
constructor() {
this.events = {};
}
on(event, listener) {
if (typeof this.events[event] !== 'object') {
this.events[event] = [];
}
this.events[event].push(listener);
return () => this.removeListener(event, listener);
}
removeListener(event, listener) {
if (typeof this.events[event] === 'object') {
const idx = this.events[event].indexOf(listener);
if (idx > -1) {
this.events[event].splice(idx, 1);
}
}
}
emit(event, ...args) {
if (typeof this.events[event] === 'object') {
this.events[event].forEach((listener) =>
listener.apply(this, args)
);
}
}
once(event, listener) {
const remove = this.on(event, (...args) => {
remove();
listener.apply(this, args);
});
}
}