JavaScript local storage

LocalStorage.js

Storage.prototype.setObject = function (_key, _value) {
  return this.setItem(_key, JSON.stringify({timestamp: new Date().getTime(), data: _value }));
};

// Clears stuff older than 2 hours
Storage.prototype.clearOld = function () {
  _t_date = new Date().getTime();
  for (var i = 0; i < Storage.prototype.length; i++) {
    if ((_t_date - this.key(i).timestamp) > 7200) {
      this.removeItem(this.key(i));
    }
  }
};

Storage.prototype.getObject = function (_key) {
  var r = null;
  try {
    r = JSON.parse(this.getItem(_key)).data;
  } catch (e) {
    r = null;
  }
  if (r && r.data) {
    return r.data;
  } else {
    return r;
  }
};

Storage.prototype.appendObject = function (_key, _values) {
  // Grab the old
  var newValues = this.getObject(_key);
  if (newValues === null) {
    newValues = [];
  }
  if (_values instanceof Array) {
    for (var i = 0; i < _values.length; i++) {
      // Fill with new if not a dupe
      if (newValues.indexOf(_values) == -1) {
        newValues.push(_values[i]);
      }
    }
  } else {
    if (newValues.indexOf(_values) == -1) {
      // Append if not a dupe
      newValues.push(_values);
    }
  }
  this.setObject(_key, newValues); // Write out
};

Storage.prototype.removeObjects = function (_key, _values) {
  for (var i = 0; i < _values.length; i++) {
    this.removeObject(_key, _values[i]);
  }
};

Storage.prototype.removeObject = function (_key, _value) {
  if (_value.iterator !== undefined) {
    // Iterable, so return with removeObjects
    return this.removeObjects(_key, _value);
  }
  var oldValues = this.getObject(_key);
  if (oldValues != null) {
    var removeIndex = oldValues.indexOf(_value);
  } else {
    // Key does not exist
    return true;
  }
  if (removeIndex === -1) {
    // Does not exist
    return true;
  } else {
    oldValues.splice(removeIndex);
    this.setObject(_key, oldValues);
  }
};