add session store that uses sessionStorage (mainmatter#1392)

* add session store that uses sessionStorage

* describe sessionStorage Store in README

README.md

@@ -545,6 +545,14 @@ stores its data in a cookie. This is used by the adaptive store if
 application uses
 [FastBoot](https://github.com/ember-fastboot/ember-cli-fastboot).__
 
+#### `sessionStorage` Store
+
+[The `sessionStorage` store](http://ember-simple-auth.com/api/classes/SessionStorageStore.html)
+stores its data in the browser's `sessionStorage`. See [the Web Storage docs]
+(https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API) for details on
+`sessionStorage` and `localStorage`. [caniuse](http://caniuse.com/#feat=namevalue-storage)
+has up-to-date information on browser support of `sessionStorage` and `localStorage`.
+
 #### Ephemeral Store
 
 [The ephemeral store](http://ember-simple-auth.com/api/classes/EphemeralStore.html)

addon/session-stores/session-storage.js

@@ -0,0 +1,105 @@
+/* global sessionStorage */
+import Ember from 'ember';
+import BaseStore from './base';
+import objectsAreEqual from '../utils/objects-are-equal';
+
+const { RSVP, $: jQuery, computed, getOwner } = Ember;
+
+/**
+  Session store that persists data in the browser's `sessionStorage`.
+
+  __`sessionStorage` is not available in Safari when running in private mode.__
+
+  __This session store does not work with FastBoot. In order to use Ember
+  Simple Auth with FastBoot, configure the
+  {{#crossLink "CookieStore"}}{{/crossLink}} as the application's session
+  store.__
+
+  @class SessionStorageStore
+  @module ember-simple-auth/session-stores/session-storage
+  @extends BaseStore
+  @public
+*/
+export default BaseStore.extend({
+  _isFastBoot: computed(function() {
+    const fastboot = getOwner(this).lookup('service:fastboot');
+
+    return fastboot ? fastboot.get('isFastBoot') : false;
+  }),
+
+  /**
+    The `sessionStorage` key the store persists data in.
+
+    @property key
+    @type String
+    @default 'ember_simple_auth-session'
+    @public
+  */
+  key: 'ember_simple_auth-session',
+
+  init() {
+    this._super(...arguments);
+
+    if (!this.get('_isFastBoot')) {
+      this._bindToStorageEvents();
+    }
+  },
+
+  /**
+    Persists the `data` in the `sessionStorage`.
+
+    @method persist
+    @param {Object} data The data to persist
+    @return {Ember.RSVP.Promise} A promise that resolves when the data has successfully been persisted and rejects otherwise.
+    @public
+  */
+  persist(data) {
+    this._lastData = data;
+    data = JSON.stringify(data || {});
+    sessionStorage.setItem(this.key, data);
+
+    return RSVP.resolve();
+  },
+
+  /**
+    Returns all data currently stored in the `sessionStorage` as a plain object.
+
+    @method restore
+    @return {Ember.RSVP.Promise} A promise that resolves with the data currently persisted in the store when the data has been restored successfully and rejects otherwise.
+    @public
+  */
+  restore() {
+    let data = sessionStorage.getItem(this.key);
+
+    return RSVP.resolve(JSON.parse(data) || {});
+  },
+
+  /**
+    Clears the store by deleting the
+    {{#crossLink "sessionStorageStore/key:property"}}{{/crossLink}} from
+    `sessionStorage`.
+
+    @method clear
+    @return {Ember.RSVP.Promise} A promise that resolves when the store has been cleared successfully and rejects otherwise.
+    @public
+  */
+  clear() {
+    sessionStorage.removeItem(this.key);
+    this._lastData = {};
+
+    return RSVP.resolve();
+  },
+
+  _bindToStorageEvents() {
+    jQuery(window).on('storage', (e) => {
+      if (e.originalEvent.key === this.key) {
+        this.restore().then((data) => {
+          if (!objectsAreEqual(data, this._lastData)) {
+            this._lastData = data;
+            this.trigger('sessionDataUpdated', data);
+          }
+        });
+      }
+    });
+  }
+});

tests/unit/session-stores/session-storage-test.js

@@ -0,0 +1,23 @@
+import { describe, beforeEach, afterEach } from 'mocha';
+import SessionStorage from 'ember-simple-auth/session-stores/session-storage';
+import itBehavesLikeAStore from './shared/store-behavior';
+
+describe('SessionStorageStore', () => {
+  let store;
+
+  beforeEach(function() {
+    store = SessionStorage.create({
+      _isFastBoot: false
+    });
+  });
+
+  afterEach(function() {
+    store.clear();
+  });
+
+  itBehavesLikeAStore({
+    store() {
+      return store;
+    }
+  });
+});