HTML5 allows web pages to work autonomously,
- Providing storage in terms of
localStorage and sessionStorage . - Providing events to tell the page when it is online / offline
- The
navigation.onLine property is a boolean that lets you know whether you are online or not. - Providing application caches.
Thus, both pages store assets that should work offline on any of these media, and checks whether it is online or offline when the page loads.
For more information, you can see http://www.html5rocks.com/en/features/offline
EDIT: Fur, index the site you linked to, works by downloading flash content, and then ping http://images.desimartini.com/allaboutrajni/config.xml every second to determine if it is all connected to the Internet. This site will not load if you disable and refresh the page.
However, a page using true autonomous functionality is, for example, http://htmlfive.appspot.com/static/stickies.html
Matt
source share