diff --git a/src/db.js b/src/db.js
new file mode 100644
index 0000000..7d81e71
--- /dev/null
+++ b/src/db.js
@@ -0,0 +1,27 @@
+(() => {
+	var local = {
+		get: (obj, cb) => {
+			if (typeof obj === 'string') {
+				setTimeout(() => cb(window.localStorage.getItem(obj)), 100);
+			} else {
+				const retVal = {};
+				Object.keys(obj).forEach(key => {
+					let val = window.localStorage.getItem(key);
+					retVal[key] =
+						val === undefined || val === null ? obj[key] : JSON.parse(val);
+				});
+				setTimeout(() => cb(retVal), 100);
+			}
+		},
+		set: (obj, cb) => {
+			Object.keys(obj).forEach(key => {
+				window.localStorage.setItem(key, JSON.stringify(obj[key]));
+			});
+			setTimeout(() => cb(), 100);
+		}
+	};
+	window.db = {
+		local: chrome && chrome.storage ? chrome.storage.local : local,
+		sync: chrome && chrome.storage ? chrome.storage.sync : local
+	};
+})();
diff --git a/src/index.html b/src/index.html
index 2c9803c..cc136d2 100644
--- a/src/index.html
+++ b/src/index.html
@@ -584,6 +584,7 @@
 
 		<!-- build:js script.js -->
 		<script src="utils.js"></script>
+		<script src="db.js"></script>
 		<script src="analytics.js"></script>
 		<script src="deferred.js"></script>
 		<script src="loader.js"></script>
diff --git a/src/script.js b/src/script.js
index 50797c9..3bb7c92 100644
--- a/src/script.js
+++ b/src/script.js
@@ -302,7 +302,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 		const d = deferred();
 		var obj = {};
 		obj[setting] = value;
-		chrome.storage.local.set(obj, d.resolve);
+		db.local.set(obj, d.resolve);
 		return d.promise;
 	}
 
@@ -322,13 +322,13 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 		});
 		// Push into the items hash if its a new item being saved
 		if (isNewItem) {
-			chrome.storage.local.get(
+			db.local.get(
 				{
 					items: {}
 				},
 				function(result) {
 					result.items[currentItem.id] = true;
-					chrome.storage.local.set({
+					db.local.set({
 						items: result.items
 					});
 				}
@@ -1008,13 +1008,11 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 		if (js) {
 			contents += '<script>\n' + js + '\n//# sourceURL=userscript.js';
 		} else {
+			var origin = chrome.i18n.getMessage()
+				? `chrome-extension://${chrome.i18n.getMessage('@@extension_id')}`
+				: `${location.origin}`;
 			contents +=
-				'<script src="' +
-				'filesystem:chrome-extension://' +
-				chrome.i18n.getMessage('@@extension_id') +
-				'/temporary/' +
-				'script.js' +
-				'">';
+				'<script src="' + `filesystem:${origin}/temporary/script.js` + '">';
 		}
 		contents += '\n</script>\n</body>\n</html>';
 
@@ -1089,15 +1087,14 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 		// CSP from affecting it.
 		writeFile('script.js', blobjs, function() {
 			writeFile('preview.html', blob, function() {
-				const frameSrc =
-					'filesystem:chrome-extension://' +
-					chrome.i18n.getMessage('@@extension_id') +
-					'/temporary/' +
-					'preview.html';
+				var origin = chrome.i18n.getMessage()
+					? `chrome-extension://${chrome.i18n.getMessage('@@extension_id')}`
+					: `${location.origin}`;
+				var src = `filesystem:${origin}/temporary/preview.html`;
 				if (scope.detachedWindow) {
-					scope.detachedWindow.postMessage(frame.src, '*');
+					scope.detachedWindow.postMessage(src, '*');
 				} else {
-					frame.src = frameSrc;
+					frame.src = src;
 				}
 			});
 		});
@@ -2014,7 +2011,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 			) {
 				hasSeenNotifications = true;
 				notificationsBtn.classList.remove('has-new');
-				chrome.storage.sync.set(
+				db.sync.set(
 					{
 						lastSeenVersion: version
 					},
@@ -2307,7 +2304,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 			$('#demo-frame').classList.remove('pointer-none');
 		});
 
-		chrome.storage.local.get(
+		db.local.get(
 			{
 				layoutMode: 1,
 				code: ''
@@ -2322,7 +2319,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 		);
 
 		// Get synced `preserveLastCode` setting to get back last code (or not).
-		chrome.storage.sync.get(
+		db.sync.get(
 			{
 				preserveLastCode: true,
 				replaceNewTab: false,
@@ -2349,7 +2346,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 				if (result.preserveLastCode && lastCode) {
 					unsavedEditCount = 0;
 					if (lastCode.id) {
-						chrome.storage.local.get(lastCode.id, function(itemResult) {
+						db.local.get(lastCode.id, function(itemResult) {
 							utils.log('Load item ', lastCode.id);
 							currentItem = itemResult[lastCode.id];
 							refreshEditor();
@@ -2389,7 +2386,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 		);
 
 		// Check for new version notifications
-		chrome.storage.sync.get(
+		db.sync.get(
 			{
 				lastSeenVersion: ''
 			},
@@ -2401,7 +2398,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 						trackEvent('ui', 'onboardModalSeen', version);
 						document.cookie = 'onboarded=1';
 					}
-					chrome.storage.sync.set(
+					db.sync.set(
 						{
 							lastSeenVersion: version
 						},
@@ -2409,7 +2406,7 @@ globalConsoleContainerEl, externalLibrarySearchInput, keyboardShortcutsModal
 					);
 					// set some initial preferences on closing the onboard modal
 					utils.once(document, 'overlaysClosed', function() {
-						chrome.storage.sync.set(
+						db.sync.set(
 							{
 								replaceNewTab: onboardShowInTabOptionBtn.classList.contains(
 									'selected'
diff --git a/src/utils.js b/src/utils.js
index ce68e50..0091128 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -180,4 +180,6 @@
 		log: log,
 		once: once
 	};
+
+	window.chrome.i18n = { getMessage: () => {} };
 })();