OS.js Iframe Application bi-directional API script

iframeapi.js

/*!
 * OS.js - JavaScript Cloud/Web Desktop Platform
 *
 * Copyright (c) 2011-2015, Anders Evenrud <andersevenrud@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @author  Anders Evenrud <andersevenrud@gmail.com>
 * @licence Simplified BSD License
 */
(function() {
  'use strict';

  var COUNT = 0;

  window.OSjs = (function() {

    var origin = {}; // Data that connects your iframe wirh OS.js app
    var listeners = {}; // The list of event listeners
    var callbacks = {};

    //////////////////////////////////////////////////////////////////////////
    // Helpers
    //////////////////////////////////////////////////////////////////////////

    /**
     * Clones given object
     */
    function cloneo(o) {
      return JSON.parse(JSON.stringify(o));
    }

    //////////////////////////////////////////////////////////////////////////
    // Private methods
    //////////////////////////////////////////////////////////////////////////

    /**
     * onload window event handler
     */
    function _onload(ev) {
      _emit('load', [ev]);
    }

    /**
     * Parse a recieved event
     */
    function _onmessage(ev) {
      if ( ev && ev.data ) {
        var data = cloneo(ev.data);

        if ( data.message === 'Window::init' ) {
          origin.wid = data.wid;
          origin.pid = data.pid;
          Object.freeze(origin);

          _emit('init', [origin]);
        } else if ( data.message === 'Window::destroy' ) {
          _emit('destroy');
        } else {
          if ( data.message ) {
            if ( typeof data.message === 'object' ) {
              if ( typeof data.message.id === 'number' && data.message.method && typeof callbacks[data.message.id] === 'function' ) {
                callbacks[data.message.id](data.message.error, data.message.result);
                delete callbacks[data.message.id];
              }
            } else {
              var msg = data.message;
              delete data.message;
              _emit('message:' + msg, data);
            }
          } else {
            _emit('data', data);
          }
        }
      }
    }

    /**
     * Emits a bound event
     */
    function _emit(type, args) {
      if ( listeners[type] ) {
        listeners[type].forEach(function(listener) {
          listener.apply(null, args || []);
        });
      }
    }

    //////////////////////////////////////////////////////////////////////////
    // Main
    //////////////////////////////////////////////////////////////////////////

    window.addEventListener('load', _onload);
    window.addEventListener('message', _onmessage, false);

    //////////////////////////////////////////////////////////////////////////
    // Public methods
    //////////////////////////////////////////////////////////////////////////

    var exports = {
      /**
       * Bind an event
       */
      on: function(type, cb) {
        if ( !listeners[type] ) {
          listeners[type] = [];
        }
        listeners[type].push(cb);
      },

      /**
       * Make a callback-type request to your OS.js app.
       */
      request: function(method, args, cb) {
        callbacks[COUNT] = cb;

        exports.send({
          id: COUNT,
          method: method,
          args: args
        });

        COUNT++;
      },

      /**
       * Send a message to OS.js app.
       * Is recieved by `Application.onPostMessage`
       */
      send: function(data) {
        if ( origin.pid ) {
          top.postMessage({
            wid: origin.wid,
            pid: origin.pid,
            message: data
          }, '*');
        }
      }
    };

    return exports;

  })();

})();