local_storage.js

var LocalStorage = LocalStorage || (function() {

  var LOCAL_STORAGE_KEY = "key";

  var connect = function() {
    if (!localStorage.hasOwnProperty(LOCAL_STORAGE_KEY) ) {
      var item = {};
      localStorage.setItem(LOCAL_STORAGE_KEY, JSON.stringify(item));
    }
  };

  var getList = function() {
    var item = JSON.parse(localStorage.getItem(LOCAL_STORAGE_KEY));
    return item[LOCAL_STORAGE_KEY];
  };

  var isValueKey = function(key) {
    var item = JSON.parse(localStorage.getItem(LOCAL_STORAGE_KEY));
    return item.hasOwnProperty(key);
  };

  var getValue = function(key) {
    var item = JSON.parse(localStorage.getItem(LOCAL_STORAGE_KEY));
    return item[key];
  };

  var setValue = function(key, val) {
    var item = {};
    item = JSON.parse(localStorage.getItem(LOCAL_STORAGE_KEY));
    item[key] = val;
    return localStorage.setItem(LOCAL_STORAGE_KEY, JSON.stringify(item));
  };

  var deleteValue = function(key) {
    var item = JSON.parse(localStorage.getItem(LOCAL_STORAGE_KEY));
    delete(item[key]);
    return localStorage.setItem(LOCAL_STORAGE_KEY, JSON.stringify(item));
  };

  return {
    connect     : connect,
    getList     : getList,
    isValueKey  : isValueKey,
    getValue    : getValue,
    setValue    : setValue,
    deleteValue : deleteValue
  };
}());