gistfile1.js

<script>
var whiteList = ["http://localhost", "http://hostel6.ru", "http://yandex.ru"];
 
window.addEventListener("message", function (e) {
  var origin = e.origin;
  var i = whiteList.length;
  var ok = false;
  while (--i >= 0) {
    if (whiteList[i] === origin) {
      ok = true;
    }
  }
  if (!ok) {
    return;
  }
  var command = JSON.parse(e.data);
  if (command[1] === "getItem") {
    e.source.postMessage(JSON.stringify([command[0], localStorage.getItem.apply(localStorage, command.slice(2))]), "*");
  }
  if (command[1] === "setItem") {
    localStorage.setItem.apply(localStorage, command.slice(2));
    e.source.postMessage(JSON.stringify([command[0]]), "*");
  }
}, false);

window.parent.postMessage("ready", "*");
</script>



function RemoteLocalStorage(iframeSrc) {
  var iframe = document.createElement("iframe");
  iframe.src = iframeSrc;
  document.documentElement.appendChild(iframe);
  var requests = {};
  var iframeWindow = iframe.contentWindow;
  var that = this;
  this.ready = false;
  window.addEventListener("message", function (e) {
    if (e.source === iframeWindow) {
      if (e.data === "ready") {
        that.ready = true;
        return;
      }
      var data = JSON.parse(e.data);
      var requestId = data[0];
      if (requests[requestId]) {
        requests[requestId].apply(null, data.slice(1));
        delete requests[requestId];
      }
    }
  }, false);
  this.iframeWindow = iframeWindow;
  this.requests = requests;
}
 
RemoteLocalStorage.counter = Math.floor(Math.random() * Math.pow(2, 30));
 
RemoteLocalStorage.prototype = {
  _request: function (callback) {
    var args = Array.prototype.slice.call(arguments);
    if (!this.ready) {
      var that = this;
      setTimeout(function () {
        that._request.apply(that, args);
      }, 50);
      return;
    }
    var requestId = ++RemoteLocalStorage.counter;
    this.requests[requestId] = callback;
    var x = Array.prototype.slice.call(arguments);
    x[0] = requestId;
    this.iframeWindow.postMessage(JSON.stringify(x), "*");
  },
  get: function (key, callback) {
    this._request(callback, "getItem", key);
  },
  set: function (key, value, callback) {
    this._request(callback, "setItem", key, value);
  }
};
 
var x = new RemoteLocalStorage("/webclient/core/util/iframe.html");
var v = Math.random();
x.set("key", v, function (value) {
  x.get("key", function (value) {
    alert("key = " + value + ", should be = " + v);
  });
});