overwrite_localStorage.js

      //our identifier to be added in front of the localstorage keys
      var myId = "myIdentifier__"

      //save the original functions
      var _setItem = Storage.prototype.setItem;
      var _getItem = Storage.prototype.getItem;

      //overwrite their function bodys forcing javascript to create new function copies
      Storage.prototype.getItem = function(item) {
        //add the identifier infront of the key
        item = myId + item
        //and call the original function
        return _getItem.call(this, item)
      }
      Storage.prototype.setItem = function(key, val) {
        //add the identifier infront of the key
        key = myId + key
        //and call the original function
        _setItem.call(this, key, val)
        //return the value to comply with the standard behaviour
        return val
      }
      //on reload we need to re-track our keys and re-define their getters
      var watchList = {}
      for (var prop in localStorage) {
        //if it's not tracked
        if(localStorage.hasOwnProperty(prop) && prop.indexOf(myId) > -1 && !watchList[prop]) {
          //add it to the watchlist with its original key name
          watchList[prop.replace(myId, "")] = localStorage[prop]
          //define a custom getter that points to our modified getItem
          Storage.prototype[prop.replace(myId, "")] = localStorage.getItem(prop.replace(myId, ""))
        }
      }

      //dirty checking loop every 100ms
      setInterval(function() {
        for (var prop in localStorage) {
          //if we have a new key or an existing key has an updated value
          if(localStorage.hasOwnProperty(prop) && ((prop.indexOf(myId) === -1 && !watchList[prop]) || (prop.indexOf(myId) === -1 && watchList[prop] && localStorage[prop] !== watchList[prop]))) {
            console.log("Saving " + prop + " = " + localStorage[prop] + " as " + myId + prop + " = " + localStorage[prop]);
            //add it to the watchlist
            watchList[prop] = localStorage[prop]
            //use our modified setter to add it with an identifier on the front
            localStorage.setItem(prop, watchList[prop])
            //remove the original
            localStorage.removeItem(prop)
            //define a custom getter that points to our modified getItem
            Storage.prototype[prop] = localStorage.getItem(prop)
          }
        }
      }, 100)