Client-Side Data Storage

Chapter 4. Working with IndexedDB

Welcome to Deep Data

So far the options we’ve worked with for storing data on the client side have been relatively simple and relatively small in nature. Now it’s time to dig deep and work with a large-scale storage system, IndexedDB. IndexedDB is a powerful storage system with a great deal of flexibility. You can store just about anything and everything you want to on the user’s browser. However, with that great power and flexibility comes an API that isn’t quite as friendly as Web Storage. You’ll also find that IndexedDB does not quite yet have great support on mobile browsers, and even when it does, it can be poorly implemented. (iOS 8, in particular, has such bad support for IndexedDB that it is simply better that you pretend it doesn’t exist.) However, in the future, IndexedDB will probably become the standard method of storing large amounts of data on the client side. For more information, and an exciting read (honest!), check out the specification at http://www.w3.org/TR/IndexedDB/.

Like every other client-side storage system described so far, IndexedDB is unique to a domain. Limits are usually poorly defined but tend to be extremely large when they exist. In general, there are no limits, but the browser will begin clearing out other IndexedDB instances if space begins to get low. Like most “persistent” systems, anything stored in the browser is inherently not persistent over eternity, but the benefits of storing data, even only semi-persistently, ...