feat(privacy): Add a storage option

src/amplitude-client.js

@@ -116,7 +116,8 @@ AmplitudeClient.prototype.init = function init(apiKey, opt_userId, opt_config, o
       expirationDays: this.options.cookieExpiration,
       domain: this.options.domain,
       secure: this.options.secureCookie,
-      sameSite: this.options.sameSiteCookie
+      sameSite: this.options.sameSiteCookie,
+      storage: this.options.storage
     });
 
     const hasOldCookie = !!this.cookieStorage.get(this._oldCookiename);

src/constants.js

@@ -21,6 +21,13 @@ export default {
   COOKIE_TEST_PREFIX: 'amp_cookie_test',
   COOKIE_PREFIX: "amp",
 
+  // Storage options
+  STORAGE_DEFAULT: '',
+  STORAGE_COOKIES: 'cookies',
+  STORAGE_NONE: 'none',
+  STORAGE_LOCAL: 'localStorage',
+  STORAGE_SESSION: 'sessionStorage',
+
   // revenue keys
   REVENUE_EVENT: 'revenue_amount',
   REVENUE_PRODUCT_ID: '$productId',

src/metadata-storage.js

@@ -5,13 +5,22 @@
 
 import Base64 from './base64';
 import baseCookie from './base-cookie';
+import Constants from './constants';
 import getLocation from './get-location';
 import localStorage from './localstorage'; // jshint ignore:line
 import topDomain from './top-domain';
 
+const storageOptionExists = {
+  [Constants.STORAGE_COOKIES]: true,
+  [Constants.STORAGE_NONE]: true,
+  [Constants.STORAGE_LOCAL]: true,
+  [Constants.STORAGE_SESSION]: true,
+};
+
 /**
  * MetadataStorage involves SDK data persistance
  * storage priority: cookies -> localStorage -> in memory
+ * This priority can be overriden by setting the storage options.
  * if in localStorage, unable track users between subdomains
  * if in memory, then memory can't be shared between different tabs
  */
@@ -23,6 +32,7 @@ class MetadataStorage {
     secure,
     sameSite,
     expirationDays,
+    storage,
   }) {
     this.storageKey = storageKey;
     this.domain = domain;
@@ -38,14 +48,23 @@ class MetadataStorage {
         domain || (writableTopDomain ? '.' + writableTopDomain : null);
     }
 
-    this.disableCookieStorage =
-      disableCookies ||
-      !baseCookie.areCookiesEnabled({
-        domain: this.cookieDomain,
-        secure: this.secure,
-        sameSite: this.sameSite,
-        expirationDays: this.expirationDays,
-      });
+    if (storageOptionExists[storage]) {
+      this.storage = storage;
+    } else {
+      const disableCookieStorage =
+        disableCookies ||
+        !baseCookie.areCookiesEnabled({
+          domain: this.cookieDomain,
+          secure: this.secure,
+          sameSite: this.sameSite,
+          expirationDays: this.expirationDays,
+        });
+      if (disableCookieStorage) {
+        this.storage = Constants.STORAGE_LOCAL;
+      } else {
+        this.storage = Constants.STORAGE_COOKIES;
+      }
+    }
   }
 
   getCookieStorageKey() {
@@ -73,6 +92,9 @@ class MetadataStorage {
     identifyId,
     sequenceNumber,
   }) {
+    if (this.storage === Constants.STORAGE_NONE) {
+      return;
+    }
     const value = [
       deviceId,
       Base64.encode(userId || ''), // used to convert not unicode to alphanumeric since cookies only use alphanumeric
@@ -84,26 +106,37 @@ class MetadataStorage {
       sequenceNumber ? sequenceNumber.toString(32) : '0',
     ].join('.');
 
-    if (this.disableCookieStorage) {
-      localStorage.setItem(this.storageKey, value);
-    } else {
-      baseCookie.set(this.getCookieStorageKey(), value, {
-        domain: this.cookieDomain,
-        secure: this.secure,
-        sameSite: this.sameSite,
-        expirationDays: this.expirationDays,
-      });
+    switch (this.storage) {
+      case Constants.STORAGE_SESSION:
+        if (window.sessionStorage) {
+          window.sessionStorage.setItem(this.storageKey, value);
+        }
+        break;
+      case Constants.STORAGE_LOCAL:
+        localStorage.setItem(this.storageKey, value);
+        break;
+      case Constants.STORAGE_COOKIES:
+        baseCookie.set(this.getCookieStorageKey(), value, {
+          domain: this.cookieDomain,
+          secure: this.secure,
+          sameSite: this.sameSite,
+          expirationDays: this.expirationDays,
+        });
+        break;
     }
   }
 
   load() {
     let str;
-    if (!this.disableCookieStorage) {
+    if (this.storage === Constants.STORAGE_COOKIES) {
       str = baseCookie.get(this.getCookieStorageKey() + '=');
     }
     if (!str) {
       str = localStorage.getItem(this.storageKey);
     }
+    if (!str) {
+      str = window.sessionStorage && window.sessionStorage.getItem(this.storageKey);
+    }
 
     if (!str) {
       return null;

src/options.js

@@ -1,3 +1,4 @@
+import Constants from './constants';
 import language from './language';
 
 let platform = 'Web';
@@ -19,7 +20,7 @@ export default {
   sameSiteCookie: 'Lax', // cookie privacy policy
   cookieForceUpgrade: false,
   deferInitialization: false,
-  disableCookies: false,
+  disableCookies: false, // this is a deprecated option
   deviceIdFromUrlParam: false,
   domain: '',
   eventUploadPeriodMillis: 30 * 1000, // 30s
@@ -39,6 +40,7 @@ export default {
   saveParamsReferrerOncePerSession: true,
   secureCookie: false,
   sessionTimeout: 30 * 60 * 1000,
+  storage: Constants.STORAGE_DEFAULT,
   trackingOptions: {
     city: true,
     country: true,

test/amplitude-client.js

@@ -24,13 +24,16 @@ describe('AmplitudeClient', function() {
   var userId = 'user';
   var amplitude;
   var server;
+  var sandbox
 
   beforeEach(function() {
     amplitude = new AmplitudeClient();
     server = sinon.fakeServer.create();
+    sandbox = sinon.sandbox.create();
   });
 
   afterEach(function() {
+    sandbox.restore();
     server.restore();
   });
 
@@ -304,8 +307,8 @@ describe('AmplitudeClient', function() {
       cookie.set(oldCookieName, cookieData);
 
       amplitude.init(apiKey, null, { cookieForceUpgrade: true });
-      const cookieData = cookie.getRaw(cookieName);
-      assert.equal('old_device_id', cookieData.slice(0, 'old_device_id'.length));
+      const cookieRawData = cookie.getRaw(cookieName);
+      assert.equal('old_device_id', cookieRawData.slice(0, 'old_device_id'.length));
     });
 
     it('should delete the old old cookie if forceUpgrade is on', function(){
@@ -323,8 +326,8 @@ describe('AmplitudeClient', function() {
       cookie.set(oldCookieName, cookieData);
 
       amplitude.init(apiKey, null, { cookieForceUpgrade: true });
-      const cookieData = cookie.get(oldCookieName);
-      assert.isNull(cookieData);
+      const cookieRawData = cookie.get(oldCookieName);
+      assert.isNull(cookieRawData);
     });
 
     it('should use device id from the old cookie if a new cookie does not exist', function(){
@@ -447,6 +450,39 @@ describe('AmplitudeClient', function() {
       assert.equal(amplitude2._sequenceNumber, 70);
     });
 
+    it('should not persist anything if storage options is none', function() {
+      const clock = sandbox.useFakeTimers();
+      clock.tick(1000);
+
+      const amplitude2 = new AmplitudeClient();
+      amplitude2.init(apiKey, null, {storage: 'none'});
+      clock.tick(10);
+
+      const amplitude3 = new AmplitudeClient();
+      amplitude3.init(apiKey, null, {storage: 'none'});
+
+      assert.notEqual(amplitude2._sessionId, amplitude3._sessionId);
+    });
+
+    it('should load sessionId if storage options is sessionStorage', function() {
+      const clock = sandbox.useFakeTimers();
+      clock.tick(1000);
+      // Disable cookies read.
+      sandbox.stub(baseCookie, 'get').returns(null);
+
+      const amplitude2 = new AmplitudeClient();
+      amplitude2.init(apiKey, null, {storage: 'sessionStorage'});
+      clock.tick(10);
+
+      // Clear local storage to make sure it's not used.
+      localStorage.clear();
+
+      const amplitude3 = new AmplitudeClient();
+      amplitude3.init(apiKey, null, {storage: 'sessionStorage'});
+
+      assert.equal(amplitude2._sessionId, amplitude3._sessionId);
+    });
+
     it('should load saved events from localStorage for default instance', function() {
       var existingEvent = '[{"device_id":"test_device_id","user_id":"test_user_id","timestamp":1453769146589,' +
         '"event_id":49,"session_id":1453763315544,"event_type":"clicked","version_name":"Web","platform":"Web"' +