Online / Offline HTML5

Writing cross-platform apps for iPhone, iPad, Android and Windows7 without lots of native coding is quite a trick to pull off. The offline capabilities of HTML5 may be the answer, but there are many issues not covered by the standard tutorials (check them out before you read on...).
Not every web application is suitable for the offline treatment and don't underestimate the amount of work involved.

Issues

• Web browser V Add to Home Screen V Native Shell.
• Logging in to your online/offline application.
• Using AJAX for Navigation.
• Encrypting local data.
• Synchronising data and encrypting transmission.
• Conflict resolution.
• Upgrading your application.

Suitability

Small applications like task lists are ideal.

Applications that query large databases are not going to work offline. You will not be able to search your million-row customer database offline. Catalogues with lots of pictures are also not going to work.
Features like this are only going to work when the app has an internet connection.

Tips and Debugging

• Firefox
• Chrome
• Do's and Don'ts