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/*
* Event emitter component.
*
* Copyright (c) 2014 Component contributors <dev@component.io>
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of the library source tree.
*
*/
"use strict";
/**
* Initialize a new `Emitter`.
*
* @api public
*/
function Emitter(obj) {
if (obj) {
return mixin(obj);
}
}
/**
* Mixin the emitter properties.
*
* @param {Object} obj
* @return {Object}
* @api private
*/
function mixin(obj) {
for (const key in Emitter.prototype) {
obj[key] = Emitter.prototype[key];
}
return obj;
}
/**
* Listen on the given `event` with `fn`.
*
* @param {String} event
* @param {Function} fn
* @return {Emitter}
* @api public
*/
Emitter.prototype.on = function (event, fn) {
this._callbacks = this._callbacks || {};
(this._callbacks["$" + event] = this._callbacks["$" + event] || []).push(fn);
return this;
};
/**
* Emit `event` with the given args.
*
* @param {String} event
* @param {Mixed} ...
* @return {Emitter}
*/
Emitter.prototype.emit = function (event) {
this._callbacks = this._callbacks || {};
const args = new Array(arguments.length - 1);
let callbacks = this._callbacks["$" + event];
for (let i = 1; i < arguments.length; i++) {
args[i - 1] = arguments[i];
}
if (callbacks) {
callbacks = callbacks.slice(0);
for (let i = 0, len = callbacks.length; i < len; ++i) {
callbacks[i].apply(this, args);
}
}
return this;
};
module.exports = Emitter;