chrome extension with cloud storage

FYI there is a new extension API to asynchronously store things like user settings, and optionally sync them across the user's other devices.

https://developer.chrome.com/extensions/storage.html

For example:

chrome.storage.sync.set({name:'Bob'}, function() {  console.log('Name saved');});// Later on...chrome.storage.sync.get('name', function(r) {  console.log('Name retrieved: ' + r['name']);});

Using sync will sync this across devices, using local will not.

Why can't you use Google App Engine? The API is pretty easy to use. Or use other Google services tied to each individual user such as Google Docs. That is how Google Chrome Sync stores bookmarks that are synchronized in your browser through Docs.

Concerning localStorage, localStorage is a key value storage API for JavaScript (Client Side). If you want to store your extension's localStorage externally online, you can iterate your storage keys/values and store them through contacting some external (whatever API you use) service. And retrieve them every time your extension starts (in background.html page).

Why would you do that though? Google Chrome Sync, synchronizes all those information by default.