Basic in-memory localStorage API for use with cmaher/backbone.hoard

in-memory-localstorage.js

// around 5MB, matching common localStorage limit
var STORAGE_SIZE_DEFAULT_LIMIT = 5000000; 

var InMemoryStorage = function () {
  this.storage = {};
  this.size = 0;
};

_.extend(InMemoryStorage.prototype, {
  setItem: function (key, value) {
    this.storage[key] = value;
    this.size += value.length;
    if (this.size > STORAGE_SIZE_DEFAULT_LIMIT) {
      // Notify Hoard that the cache is full.
      // This will trigger a cache invalidation.
      throw new Error("On-Page Cache size exceeded");
    }
  },

  getItem: function (key) {
    var value = this.storage[key];
    if (_.isUndefined(value)) {
      value = null;
    }
    return value;
  },

  removeItem: function (key) {
    var value = this.getItem(key);
    delete this.storage[key];
    if (value != null) {
      this.size -= value.length;
    }
  }
});

Backbone.Hoard.backend = new InMemoryStorage()