dropzone.js

/*
 *
 * More info at [www.dropzonejs.com](http://www.dropzonejs.com)
 *
 * Copyright (c) 2012, Matias Meno
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */


// The Emitter class provides the ability to call `.on()` on Dropzone to listen
// to events.
// It is strongly based on component's emitter class, and I removed the
// functionality because of the dependency hell with different frameworks.
class Emitter {
  // Add an event listener for given event
  on(event, fn) {
    this._callbacks = this._callbacks || {};
    // Create namespace for this event
    if (!this._callbacks[event]) {
      this._callbacks[event] = [];
    }
    this._callbacks[event].push(fn);
    return this;
  }


  emit(event, ...args) {
    this._callbacks = this._callbacks || {};
    let callbacks = this._callbacks[event];

    if (callbacks) {
      for (let callback of callbacks) {
        callback.apply(this, args);
      }
    }

    return this;
  }

  // Remove event listener for given event. If fn is not provided, all event
  // listeners for that event will be removed. If neither is provided, all
  // event listeners will be removed.
  off(event, fn) {
    if (!this._callbacks || (arguments.length === 0)) {
      this._callbacks = {};
      return this;
    }

    // specific event
    let callbacks = this._callbacks[event];
    if (!callbacks) {
      return this;