wormhole - simple cross-domain ajax with a convenient interface

wormhole_backend.js

// backend
$(document).ready(function() {
  // the server sets parentUrl in the page it serves, based on the http-referer
  var windowProxy = new Porthole.WindowProxy(window.parentUrl + "/proxy.html");

  function send(data) {
    windowProxy.postMessage(JSON.stringify(data));
  }
  
  windowProxy.addEventListener(function(event) {
    var data = $.parseJSON(event.data),
        requestId = data.requestId,
        params = data.params;
    
    console.log(event);
    
    $.ajax(params)
     .done(function(data, textStatus, jqXHR) {
        send({
          type: 'response',
          requestId: requestId,
          success: true,
          data: data,
          textStatus: textStatus
        });
      })
     .fail(function(jqXHR, textStatus, errorThrown) {
        send({
          type: 'response',
          requestId: requestId,
          success: false,
          textStatus: textStatus
        });
    });
  });
  
  send({type: 'ready'});
});

wormhole_frontend.js

// frontend
App.Wormhole = Ember.Object.extend({
  init: function() {
    var target = "wormhole_iframe";

    // create the iframe
    this.iframe = $('<iframe id="' + target +
                        '" name="' + target + 
                         '" src="' + this.backendUrl + 
                       '" style="width: 0; height: 0; border: none; display: none;"></iframe>');
    $('body').append(this.iframe);
    
    // create a porthole.js proxy window to send and receive message from the vault iframe
    this.windowProxy = new Porthole.WindowProxy(this.backendUrl, target);

    // handle messages based on their type
    var self = this;
    this.windowProxy.addEventListener(function(message) {
      var data = $.parseJSON(message.data);
      switch (data.type) {
        case "ready": return self.onReady(data);
        case "response": return self.onResponse(data);
        default: throw Error("unknown message type: " + data.type);
      }
    });
  },
    
  linked: false,
  pending: [],
  nextRequest: 1,
  deferreds: {},
  
  // make an ajax request through the porthole
  ajax: function(params) {
    var requestId = this.nextRequest;
    this.nextRequest += 1;

    var deferred = $.Deferred();
    this.deferreds[requestId] = deferred;
    
    var request = {requestId: requestId, params: params};
    if (this.linked) {
      this.sendRequest(request);
    } else {
      this.pending.push(request);
    }
    return deferred.promise();
  },
  
  // send a request by posting it to the hidden iframe
  sendRequest: function(request) {
    this.windowProxy.postMessage(JSON.stringify(request));
  },

  // handle the initial ready message indicating that the iframe has loaded successfully
  // we mark the link as being established and send any requests that are pending
  onReady: function(data) {
    this.linked = true;
    for (var i = 0; i < this.pending.length; i++) {
      this.sendRequest(this.pending[i]);
    }
  },
  
  // handle responses to requests made through the wormhole
  onResponse: function(data) {
    var deferred = this.deferreds[data.requestId];
    delete this.deferreds[data.requestId];
    
    if (data.success) {
      deferred.resolve(data.data, data.textStatus);
    } else {
      deferred.reject(data.textStatus, data.errorThrown);
    }
  }
});