Add safe wrappers around localStorage

src/__tests__/LDClient-test.js

@@ -110,6 +110,53 @@ describe('LDClient', function() {
       });
     });
 
+    it('should handle localStorage getItem throwing an exception', function(done) {
+      sandbox.restore(window.localStorage.__proto__, 'getItem')
+      sandbox.stub(window.localStorage.__proto__, 'getItem').throws()
+
+      var warnSpy = sandbox.spy(console, 'warn');
+
+      var user = {key: 'user'};
+      var client = LDClient.initialize('UNKNOWN_ENVIRONMENT_ID', user, {
+        bootstrap: 'localstorage'
+      });
+
+      client.on('ready', function() {
+        expect(warnSpy.calledWith(messages.localStorageUnavailable())).to.be.true;
+        done();
+      });
+
+      requests[0].respond(
+        200,
+        { 'Content-Type': 'application/json' },
+        '[{"key": "known", "kind": "custom"}]'
+      );
+
+    });
+
+    it('should handle localStorage setItem throwing an exception', function(done) {
+      sandbox.restore(window.localStorage.__proto__, 'setItem')
+      sandbox.stub(window.localStorage.__proto__, 'setItem').throws()
+
+      var user = {key: 'user'};
+      var client = LDClient.initialize('UNKNOWN_ENVIRONMENT_ID', user, {
+        bootstrap: 'localstorage'
+      });
+
+      var warnSpy = sandbox.spy(console, 'warn');
+
+      requests[0].respond(
+        200,
+        { 'Content-Type': 'application/json' },
+        '[{"key": "known", "kind": "custom"}]'
+      );
+
+      client.on('ready', function() {
+        expect(warnSpy.calledWith(messages.localStorageUnavailable())).to.be.true;
+        done();
+      });
+    });
+
     it('should not update cached settings if there was an error fetching flags', function(done) {
       var user = {key: 'user'};
       var json = '{"enable-foo": true}';
@@ -140,7 +187,7 @@ describe('LDClient', function() {
         bootstrap: {} // so the client doesn't request settings
       });
 
-      var warnSpy = sinon.spy(console, 'warn');
+      var warnSpy = sandbox.spy(console, 'warn');
 
       requests[0].respond(
         200,
@@ -151,7 +198,6 @@ describe('LDClient', function() {
       client.on('ready', function() {
         client.track('known');
         expect(warnSpy.calledWith('Custom event key does not exist')).to.be.false;
-        warnSpy.restore();
         done();
       });
     });
@@ -184,7 +230,7 @@ describe('LDClient', function() {
         bootstrap: {} // so the client doesn't request settings
       });
 
-      var warnSpy = sinon.spy(console, 'warn');
+      var warnSpy = sandbox.spy(console, 'warn');
 
       requests[0].respond(
         200,
@@ -195,7 +241,6 @@ describe('LDClient', function() {
       client.on('ready', function() {
         client.track('unknown');
         expect(warnSpy.calledWith(messages.unknownCustomEventKey('unknown'))).to.be.true;
-        warnSpy.restore();
         done();
       });
     });

src/index.js

@@ -6,6 +6,7 @@ var Requestor = require('./Requestor');
 var Identity = require('./Identity');
 var utils = require('./utils');
 var messages = require('./messages');
+var store = require('./store');
 
 var flags = {};
 var environment;
@@ -174,7 +175,7 @@ function updateSettings(settings) {
   flags = settings;
 
   if (useLocalStorage) {
-    localStorage.setItem(lsKey(environment, ident.getUser()), JSON.stringify(flags));
+    store.set(lsKey(environment, ident.getUser()), JSON.stringify(flags));
   }
 
   if (keys.length > 0) {
@@ -258,11 +259,12 @@ function initialize(env, user, options) {
   }
   else if (typeof(options.bootstrap) === 'string' && options.bootstrap.toUpperCase() === 'LOCALSTORAGE' && typeof(Storage) !== 'undefined') {
     useLocalStorage = true;
-    // check if localstorage data is corrupted, if so clear it
+
+    // check if localStorage data is corrupted, if so clear it
     try {
-      flags = JSON.parse(localStorage.getItem(localStorageKey));
+      flags = JSON.parse(store.get(localStorageKey));
     } catch (error) {
-      localStorage.setItem(localStorageKey, null);
+      store.clear(localStorageKey);
     }
 
     if (flags === null) {
@@ -272,7 +274,7 @@ function initialize(env, user, options) {
           emitter.emit(errorEvent)
         }
         flags = settings;
-        settings && localStorage.setItem(localStorageKey, JSON.stringify(flags));
+        settings && store.set(localStorageKey, JSON.stringify(flags));
         emitter.emit(readyEvent);
       });
     } else {
@@ -285,7 +287,7 @@ function initialize(env, user, options) {
           console.error('Error fetching flag settings: ', err);
           emitter.emit(errorEvent)
         }
-        settings && localStorage.setItem(localStorageKey, JSON.stringify(settings));
+        settings && store.set(localStorageKey, JSON.stringify(settings));
       });
     }
   }

src/messages.js

@@ -2,6 +2,9 @@ module.exports ={
   invalidKey: function() {
     return 'Event key must be a string';
   },
+  localStorageUnavailable: function() {
+    return 'localStorage is unavailable';
+  },
   unknownCustomEventKey: function(key) {
     return 'Custom event "' + key + '" does not exist'
   }

src/store.js

@@ -0,0 +1,27 @@
+var messages = require('./messages');
+
+function get(key) {
+  try {
+    return window.localStorage.getItem(key);
+  } catch (ex) {
+    console.warn(messages.localStorageUnavailable());
+  }
+}
+
+function set(key, item) {
+  try {
+    window.localStorage.setItem(key, item);
+  } catch (ex) {
+    console.warn(messages.localStorageUnavailable());
+  }
+}
+
+function clear(key) {
+  set(key, null);
+}
+
+module.exports = {
+  get: get,
+  set: set,
+  clear: clear,
+};