Offline Applications and Client‐Side Storage
Nicholas C. Zakas · 2015
One of HTML5's focus areas is enabling offline web applications. An offline web application still works even when there is no Internet connection available to the device. Browsers now have the ability to detect when a user has gone offline and fire events in JavaScript so that our application can respond. The application cache allows us to specify which files should be made available offline. A JavaScript API is available for determining what the application cache state is and how it may be changing. Traditionally, client-side storage was limited to using cookies, small pieces of information that could be set from the client or server and transmitted along with every request. JavaScript provides access to cookies through document.cookie. Web Storage defines two objects to save data: sessionStorage and s. IndexedDB is a structured data storage mechanism similar to an SQL database.