With advances in HTML5, web apps no longer require an Internet connection — thanks to HTML5′s support of client-side storage, web apps now can run offline in today’s browsers.
“An HTML5 offline application is simply a website that has been configured to store data locally in the user’s browser so that some or all of its functionality is available when the device is not connected to the Internet,” mobile consultant and web evangelist Jonathan Stark explained in a recent interview. “There are several technologies in the HTML5 family of specs that make offline web apps possible — Offline Application Cache, Web SQL Database, Web Storage, etc.”
Browser support, of course, is an essential consideration. “Support for the most critical offline technologies (Offline Application Cache, Web Storage, and Web SQL Database) is very good across both desktop and mobile browsers,” Stark said. “Even so, I recommend treating offline support as a progressive enhancement — if offline support is an absolute requirement for your web app, you’ll probably have to document which browser/OS combinations are explicitly supported and provide ‘best effort’ support for everything else.”